I'm trying to diagnose a throttle response problem that the car has. from idle, it hesitates on acceleration until it is fully warmed up. It doesn't fully stall, but it almost does. It idles fine, and when it is warm it runs with solid throttle response.

I first checked the throttle body. It was filled with gunk, so I cleaned it out and put a new gasket on. This didn't seem to change matters much, maybe just a little. the problem persisted.

Around this time I was in at the shop and asked the mechanic about a buzzing sound from under the driver's side. He said the fuel pump was starting to go bad. Sure enough, the sound was much quieter with a full tank of gas. I wasn't sure when the PO replaced the fuel filter, so I put a new one in, figuring it may be very dirty, and restricting fuel flow, perhaps even causing the pump to start to die. This also didn't solve my throttle issue.

I've read that improper fuel pressure, perhaps because of a bad FPR, can screw with the mixture until the 02 sensor sorts things out. Is it possible that a working, but noisy/sickly fuel pump would cause my situation? Or is the fuel pump a work-or-doesn't-work part? What would the next diagnostic step be (other than taking it to the mechanic...just paid $$$ to have my suspension bushings replaced...)? Is it worth cleaning the AMM?

thanks