[00 SS]

My daily driver is an 88 Buick Park Ave. Lately, I've been having trouble with it running right when the engine is hot and I restart it. Almost seems to be vapor locking, but it's multiport fuel injection. Ocationally when this happens, I can bleed some "air" or maybe fuel vapor out of the schrader valve on the rail which sometimes helps, sometimes not. It starts, then idles like it's missing badly and the engine won't rev up. So far, I've been able to coax it into working and getting me where I need to go, but I at a bit of a loss as to why this is happening all of a sudden (the last week or so). The weather hasn't been too bad lately and it was certainly hotter earlier in the summer and it ran fine. It seems OK while I'm driving and after it's been allowed to cool down all the way.

The recent maintenance includes:
new fuel filter
new plugs
new coil packs and igniton contol module
Removed and cleaned injectors (really were pretty clean to begin with)

My ideas:
fuel pump is low on pressure allowing the fuel to vaporize in the rail while sitting after driving
Bad presure regulator not holding the pressure up while sitting after driving, or sticking not allowing the vapor to exit and return to the tank.

Any insight or ideads would be appreciated.

[CrashTestDummy]

Yep. Possibly a fuel pump, possibly not. First steps would be to get a fuel pressure gauge and hook it up, and check the fuel pressure:
1. cold, turn key on, watch the fuel pressure when the pump spins up and then stops.
2. after that, turn the key off and watch the pressure. It should hold for a while. If you can see the pressure drop, the check valve, which is usually part of the fuel pump assembly, may be bad.
3. start and run the car, see what the pressure is.
4. remove the vacuum hose on the fuel pressure regulator and check for fuel in this line (blown fuel pressure regulator diaphram), and check to see what the pressure goes to. It should go up.

I am not sure what the pressure readings should be. You'll need to search for the info online, or get a FSM. I'm suspecting that 1. will be around 40 PSI, 3. should be around 35-40 psi, and 4. should be around 40-42 psi, but I don't know for sure.

If that all passes, try to get a ECM scan. Some autoparts places may offer it, but since it's not OBDII, your options may be limited. You should be able to get the ECM to flash out any stored codes, which may, or may not tell you anything.

Other than that, you're just throwing parts at it.