hesitation when accelerating

[josherino]

I have a 90 gsx that hesitates/jolts when accelerating, it is especially noticible around the 2000 to 3000 rpm band and also when the car is not completely warmed up. what is causing this hesitation? could it be a bad fuel pump?

 

[marcmsj]

could be a number of things... misfires maybe?

 

[josherino]

how can you tell the difference between misfiring and a slight fuel cut b/c I know my stock fuel pump is almost dead?

 

[cookmaster30]

you also might want to do a leak check. i had a real bad studder and did a leak check and solved most of my problems. also check your plugs and wires. good luck.

 

[josherino]

i do hear a major vacuum whistling noise, but i have not been able to find it yet