I've got a stutter during acceleration in an '87 5000 S 2.3L. It does it often, but mostly under heavy acceleration, and stops at around 3000 rpms. I don't think it's the clutch because it even does it in neutral when parked and when it stutters the rpms don't increase. I also just replaced the fuel pump so it's probably not that. Anyideas?? All help is appreciated

 

vacum leaks .. throttle position sensor ... idle stabilizer valve