Hi everyone, thanks for the great advice. Here goes: I bought an 87 k5 about 3 months ago, and noticed that it never heated up (the engine or my heater). So after checking the thermostat and recognizing that it was a 160 degree t-stat, I changed it to a 195. Now i got plenty o' heat, but now it pings at/near WOT and make a metalic "flitter" kinda sound (?). Then the check engine light comes on (Goes off after shutting down then restartin'). *As long as I am fairly gentle with the pedal, no pinging or check engine light. I am going to change the t-stat back to the 160 degree one, because I think there may have been a "chip-transplant" that I was not aware of. Does this theory pan out with anyone else?? Also curious if I have to reset timing or anything... thanks, James 87 k5, new (10K) GM goodwrench 350 with stock TBI on an Edelbrock Performer TBI intake.