Stumbling issues

At Hallett the car would hesitate and stumble getting out of corners.
It seemed like a mid RPM issue, going away above 4000.
Fuel pressure was steady around 40 while stumbling, on a full tank.
It was always heat related, happening after a few laps.

So far I've replaced: plugs, wires, cap, rotor, ignition control module, and coil. All looked or tested fine.
Replaced fuel filter at track.. no change. I could change the fuel pump, but with steady pressure, its probably not the issue.

Bring on the GM jokes along with some advice. :)

Nick,
HEI ignition is "hall effect". If the magnet that senses the pointer on the distributor has cracked, it may be separating, creating two "norths" and two "souths" just enough at the mid-RPM range to throw off the spark events. Once the engine is above a certain RPM, it cannot "crap out" fast enough to make a difference.

I'd throw a reman distributor in it and see how she runs.

Second idea... kinda simple... Did you pull the trouble codes, if any?

Any codes were cleared when the MD was switched off. :?

Thanks to the help of my f-body bretheren, we got the car redyno'd today after a distributor change along with the aforementioned "tuneup". Seems to be fine. We'll find out next weekend.

The monority, step children of this series have to stick together.

Glad to hear the issue is hopefully resolved Nick, we'll see ya in 1-week!!