Gentlemen, I am at my wit's end and need help. Here's what's going on.

I have a dibilitating hesitation/stutter when depressing the gas pedal after starting up the car (after its warm or driven already) and giving it the initial gas to move forward.

Car always starts, no problem. In the am, I can put her in D, drive to work and practically never experience this problem. Problem arises FOR EXAMPLE:

30 minutes later I go out to the car again. Starts no problem. Its idling ok. I can put it in reverse, back out of a parking space, then as soon as I put it in D, and give it gas it feels like someone has pinched the fuel line. I'll tap the gas pedal 3, 4, 5 times to give it gas, while in neutral and its like its choking. Like gas wants to get through, but it cant. After the 4th or 5th tap...VROOMM. Its totally fine. Its like it has to "work something out of its system"

THen it runs perfect. Won't do it as I drive, at all. Does this again after I park for 15 minutes, 45 minutes, 2 hours. Seems to rarely do this if its been parked for 6-8 hours. But it has a few times.

I'm thinking vapor? THe car has been like this since I bought it in November 07 (133k, 89, 245, Auto).

~Things I've done that could be related: new plugs, rotor, cap, wires.
~cleaned TB and adjusted TPS correctly
~new air filter, AMM seems to operate fine, cleaned IAC valve

I have not touched the injectors nor the intake manifold yet.

I bought a check valve for the main fuel pump, but I found out that my pump had been replaced (at some point by the PO) with an aftermarket pump that sort of has a check valve...in other words, it has the valve, but there are no "insides" or valve parts inside it. The check valve I bought didnt fit on my aftermarket fuel pump.

Even though my car starts all the time and idles fine, could this still be vapor -lock related. Ie check valve or fuel pump?

Please ask me any additional questions based on your hunches. I've got to figure this one out as it is very very annoying and I worry one day something will conk out, not to mention the stress on parts while I tap the gas and it conks, sputters and gasps. Again, it feels like someone's stuck a needle in all 4 injectors at once, then pulls the needles all out at once when it finally clears.

Ugh. Only way to describe it...now I'm going to the Pick n Pull for a hood hinge as mine snapped off on me this morning!
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89 245 'loaded' with a Great Pyrenees