I have a 94 z 6 spd with headers and gm hot cam setup also has MSD opti-spark and wires with stock coil. Under part throttle cruise the car stumbles then after a few seconds it clears then accelerates cleanly then repeats. Plugs look really nice, put the datamaster on it , drove it around and no codes displayed. Vacuum at idle is 14.5 +- .5 steady no bouncing. Car at idle is great. There is a faint smell of fuel but no evidence of leaks. Dont currently have access to a Fuel press gauge.

Any help would be appreciated
Later

 

I had a problem similar to that when I first got my car. I cleaned my MAF and put an LT4 Knock Module in, and it stopped. If you still have the stock LT1 Knock Module, it may be picking up false knock from your upgraded valvetrain for the hot cam, and causing it to retard timing. Mine was retarding timing because of exhaust leaks, and just the extra underhood noise from having headers.

 

replace the front o2 sensors

 

its a 94 so it only has front o2's

 

LT4 valvetrain needs LT4 Knock module. Why they made them.

 

What happens if you unplug the knock sensor?? How will the car run?? Is there a default timing setting??
Thanks
BobH