I have an 89'IROC with a tpi 350 motor. It has edelbrock aluminum heads, headers, and I installed a Crane Cams Powermax 2031 recently. The lift is In.438"/Ex.452" and In208/Ex214. When the engine is cold or after it has sat for 20min it runs nice. But after if has been run for ten minutes or so it develops a strange jerky and slow acceleration. At first I though I was setting off the knock sensor but even when the fuel pressure is up to 60psi it still does it. I noticed this problem before but it was never this bad. I tried the timing at 6 and 8 degrees but there was no difference. When I reinstalled the distributor I was in a rush to get it back together so I wasn't very technical about how the rotor was pointing to the no. 1 piston. Could this be the cause?

Thanks