Chevrolet Repair: Off idle stall, vacuum leak, egr system

Question
I have a 94 camaro with a 3.4 V6. The problem I'm having with it is a hesitation when first hit the gas. This does not occur on a cold engine, just after it warms up. It will go to stall then take off. The EGR system has just been cleaned and the car has been check over by a mechanic who told me it could be a weak fule pump. The presure holds and 41 then drops to 35 when the gas is hit, then goes right back to 41. unpluging the fuel presure regulator solves the problem. What could be the right fix for this? I've also noticed that it does not hold any vacum once the car is turned off. Not even a few seconds. Could a large vacum leak cause a hesitation off idle? It will do the same thing on the highway if the gas is pushed to the floor quickly.

Answer
Yes it could be a vacuum leak causing the problem. Low fuel pressure or low volume would also cause that. Make sure the EGR valve is operating properly. If the EGR valve is defective it could be opening too much or too fast on accel causing the problem too.