Engine Trouble need suggestions

[mdmicon]

my car is having a problem and I've been chasing it down and cant find it. The car isn't coming up fully in RPMs when it hit about 4500 it dies. The weird part is that when it sticks here if I keep playing with the throttle (lefting off then nailing it again over and over) I can get it to come on up but by this time I'm generally at the end of the straight stretch and miss most of my power.

I'm running a weber carb and a MSD ignition. The carb was cleaned and rebuilt and that didn't fix it. I also just switched to the MSD hoping it was a ignition problem but I had the same results with the MSD.

I replaced the fuel pump also thinking maybe I wasn't getting the fuel I needed.

I'm now thinking either the carb is having another problem or that the distributor shaft could slightly be out causing it to hit the pickup under load. When the distributer is out of the car it spins freely.

I'm lost and this is very frustrating, anyone have any suggestion?

[rad15E]

are you running a stock dist.

[mdmicon]

Yes it is a stock distributor that has been modified

[rad15E]

modified how .has the advance curve been corrected.if not thats your problem

[mdmicon]

Yes it's been welded so the advance curve is corrected