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
No codes, No faults