Hello, nice to find a decent Bonneville forum.
I'm having a serious issue with my 95 SE with the optional Series 1 L67.
At 4000 rpm, the ECU drops almost all ignition timing. It only occurs under I would say >1/4 throttle and after the ECU is in closed loop. Its not a componet heating up because you can pull over, shut the car off, restart, and it drives fine (until it kicks in to closed loop).
My Auto X-ray is showing-
Weak cylinder 4 (???)
Ignition timing dropping to close to ZERO
Knock sensor -1 to -4 degrees
O2 850mv
TPS 4.25v
No codes, No faults

Any Ideas? :?

Welcome to the club '95SCSE, I was away on vacation and just now got back. It is good to see another L67 equipped 95 SE. I was getting pretty lonely here. I think it will help if we move this topic to the Induced section. I will do that now. Maybe someone will pipe up and give you a hand. I have never experienced your symptoms before so we will post it to the experts.

BTW, update your signature with all the pertinent details of your car: year, trim, engine, miles, color, speacial options, mods, etc.