[s-cars] New stumble.....Altitude related?

[Jim Fleischer]

Hey guys,

After 6 months of fairly trouble-free motoring at WOT and plenty of trips all over the west, I happened on a WOT stumble last week here in the mountains (7500 ft. elev.) of Colorado.  Here's the kicker......went to Denver (5200 ft elevation) a few days ago and the stumble wasn't near as bad down there, still there, but inconsistent and far less noticeable.  I have about 7500 miles on new NGK plugs and boots (solved my stumble over the summer) and am wondering if it may finally be a coil.  Car runs good at idle, and no stumble at partial throttle under load and acceleration on the highway well past the legal limit here at 7500-8000 ft, but WOT stumble is consistent at all RPM.  I'll check out possible boost leaks, of course, but curious if someone out there who did a coil pack conversion has a known good stock coil pack or two they'd sell cheap.  Should probably have one in the car anyway.

Any other suggestions welcome of course.  Maybe start with checking the plugs again?

Thanks for the help, as always.

Jim Fleischer
'95 s6 avant with 105K