Engine problems
 

Okay fellas, heres the deal. Im having an engine problem and figured Id post here in hopes someone might be able to shed some light.

The problem is this. When driving the car I usually shift at about 2500 to 3000 rpms in every gear. Well, it has come to be that the shift from first to second is flawless. But when accelerating in second to get to the next shift point it hits about 2000 rpms and the car starts to buck horribly. Okay, now what. Well I park the car and rev it up to see if it does it in neutral. It does not do it in neutral, at 2000. Instead it does it at 4000. Its almost like its hitting a rev limiter, but last time I checked that isnt til 6500. It just goes back and forth between 3k and 4k. Anyhow, anyone got any ideas?

Oh, almost forgot...Car is:
1985.5 944
N/A 2.5L inline 4
completely stock.

Do you think your car is missing some serious power?, i.e. does it do less then 9s for 0-60 and can do 130mph easily?
If so do an engine compression test. This will give you some clues. Does your car idle perfectly? You probably need to answer some of this questions before proceeding in finding the problem with your engine.