[Bleyseng]

First thing Iwould check is the timing and the distributor. Sounds like it might be off. It should be 27' BTDC @3500rpms with hose off and plugged. Make sure you have the vacuum adv hose and the retard hose in the right places too. The vac adv is the port that is above the throttle plate and goes the the big silver can on the distributor.
Second is the MPS the right one for your car? It should be a number ending in 037. It is for that year only! It might be that you are running lean so is doesn't have the pick up you are looking for.
What condition are all the hoses on the engine? The big ones on the manifolds to the plenum tend to leak as they get old, so check em out. I use starting fluid to find leaks, spray just a small amount at the areas you think might leak!!! Alot of it will trick you by going into the TB and giving a false rpm increase.
Geoff