Just to get it out of the way, yes I did search intensely on the forum, but couldn't find anything that would help matters.
I have the issue, that my 89 TBI 360 LA Ramcharger starts immediately when its cold, on the first turn of the starter. If it's warm (even when it sat in the sun at 90°F) it barely will start. On the first turn of the starter it seems to start and then falls back to cranking for about 5-10s until it hesitantly starts. Once it  runs all's fine again, normal idle and so on.
The starter turns very well and fast, also when hot.
The only thing I had, once in a while is, that it bogged a little when I tried to accelerate harder. If I then modulated the gas pedal I could get around it and it worked fine. Didn't happen often, though. I ran fresh gas and injector cleaner, now it's not noticeable anymore.
Gas mileage wise, I haven't calculated it, but it seems in the regular range. A 4.5hrs drive through the mountains used approx 2 index marks on the fuel gauge.

This is a list of what I did to the car the last two months:
   - Replaced all fuel lines (not the one in the tank, they look new and the stamp on the fuel pump lets me assume, that it's one from 2016, Bosch)
   - I checked the fuel pressure, perfectly fine in idle and also on higher rpm(no load)
Fuel pressure after time:
4min = 10psi
7min = 8psi
30min = 6psi
   - Timing has been checked
   - New harmonic balancer (verified TDC with marks)
   - Spark plugs are fine
   - Spark plug wires tested for resistance = good
   - Visual check of both injectors, spray a cone, though not very fine (what does one expect at such a low fuel pressure, so I deemed it ok. Especially as the fuel only pours on the throttle blades anyway)
   - Fresh oil, new oil pan, new oil pump
   - New Thermostat
   - Checked both temperature sensors, coolant and TB. Both within specification:
     Coolant sensor
     21C = 11.3 kOhm
     53C = 3.7 kOhm
     93C = 0.92 kOhm

     TB sensor
     21C = 8.8 kOhm
     53C = 2.7 kOhm
     93C = 0.73 kOhm
   - New PCV valve
   - New O2 Sensor (Bosch)
   - Measured timing chain play, like brand new
   - New battery
   
   
According to the PO the engine has been replaced about 10 years ago, but only 2000Mi. The story could be true, at least I found tags on the engine that state it had been rebuilt. When I had the oil pan of to replace the oil pump, the rear main bearing looked brand new.

I haven't done a compression check yet on the engine.

I have the impression, that the car is way to quiet, it only has the catalyst converter, no muffler. I figure that the exhaust valve on the passenger side doesn't work anymore, I fixed it in the open position. Didn't make a difference performance wise, but a least it sound like a V8 at idle. As the clamps for the cat a rusted badly, I would have to cut them off. I have the new clamps here, but no tool to cut off the bolts. May the cat is clogged? But that doesn't seem to have an impact on starting in my opinion.

I have no error code.

From my understanding the control module uses atmospheric pressure and coolant temperature to decide how much fuel it needs for a startup. As the coolant sensor seems to be ok I could only imagine the MAP sensor to be bad, besides the control module itself.
(I have some experience with EFI, had a Megasquirt on my car for 1.5 years which I installed and programmed myself)

On the throttle body there's a nipple for a heated air inlet, mine is plugged with a screw, doesn't look stock. I can't find a connection for it though. Manual P.707

It starts perfectly if I restart it within a minute after shutting it of.
It starts faster if I floor the gas pedal.
So I checked the O-rings of the injectors, one had a very little scuff mark, probably not even a cause for a leak. I replaced it anyway, didn't make any difference.

Any other suggestions I may could check? I have to sell the car unfortunately as soon as I have the new title in hand. Had planned to keep it for quite a while. I'd like to sort this out before selling, would be nice.

I found some information on the forum:
https://ramchargercentral.com/vehicle-help/hard-starting-after-warm-up/msg1860694/#msg1860694
But I can't / won't replace the starter as I have to sell it. And mine turns very well, same engine revs as cold. On top it starts faster if I floor the gas pedal, doesn't seem to be connected to the starter.

- I checked the fuel pressure, perfectly fine in idle and also on higher rpm(no load)
Fuel pressure after time:
4min = 10psi
7min = 8psi
30min = 6psi

Isn't this very low for a TBI?

the po stated psi after time , so after 4 mins of what ? OFF time it drops to 10 psi ? or is that 4 mins of running time ?

Took that to mean residual pressure after shutdown,those #s seem ok.

That would be a different story then. If it's just bleed down pressure, then the next thing I'd consider is a bad Hall-effect sensor. It can be failing and won't throw codes.

when its warm and you want to restart , try this , step all the way down on the gas pedal and hold it there , then crank it . does it start a little better ? if so look for a leaking o ring or throttle body , allowing raw fuel to drain into manifold when OFF , creating a "flooded" condition .  Yes depressing the pedal all the way while cranking tells the pcm you are clearing a flooded condition , and it does NOT supply more fuel , just air ... this leaking could also account for the pressure drop off when OFF

WHOA ....... you ALLWAYS floor it when starting warm ? , and if it sits too long its hard starting well thinkabout that ............ the fuel regulator / check valve slowly leaks off pressure ,( acceptable) You turn on the key , pressure back , you FLOOR it ( as YOU say ) the pcm shuts off ALL fuel to engines intake because you foot says to do that , engine don't start ......... NO fuel ...... IN that case , keep your foot under the seat , turn key .... what happens ?

Yes, I do floor it when warm, because it starts faster. It takes approximately 10-15s without flooring, maybe 5-8s when I floor it and it starts "healthier".

But if the leak is somewhere, where the fuel drips into the intake, it has a flooded condition, therefore the flooring when hot helps.
It would also explain, why the car jumps to life when cold, richer = better (if not too much)

Thanks for all the help.
But due to the COVID situation I had to make the decision to sell the Ramcharger.


I haven't found the solution to it's warm start problems.

Because of lack of work? Really getting sick of this fake covid bullshit

Call it what you want, but it's not fake. i got a bunch of dead 40 year olds to back me up

a tbi that starts with 5 seconds of crank , may not of had such a big problem ..