boggs down on acceleration on 1995 Pontiac Grand Am

The water pump went out on the car and it had to sit for 3 months, it ran ok except overheating. Nw that that is fixed, it will not accelerate. I have to pump the gas pedal to get it to go, once over 50 mph it runs ok. It also stalls at lights. We have put 1/2 tank of 93 octane, Heet, Octane Booster and Injector Cleaner in the tank but no help. Replaced the fuel filter and checked vacuum hoses.... NOTHING HELPS.

1 answer
I have seen guys bump off a vacuum line while doing this job on the 2.3 liter. Check all of your vacuum lines and connections. Is there a Service Engine Soon Light on?