"Bob" wrote in message news:cagi3a$3c5

Any other ideas why it might ping at sea level?

Thanks!

I recall years ago having to advance timing approx 1 degree per thousand
feet to compensate for altitude. This was when relocating cars from around
sea level to Denver. I would think the opposite would hold true. If you're
set up properly for 6000 feet at Tahoe, try retarding about 5 degrees when
you go to sea level.