Ok, this may be a little off topic being it on my '86 C10 4.3L v6 engine, but I thought I might draw upon the more experianced in this area: I've been having what feels like the engine is misfiring, so I replaced the cap, rotor, coil, pickup coil, module, plugs, wires and it got better, but still not right. The thing pops while idles and is spitting fire, like it's running rich, very rich. I don't think it carb (I could be wrong) it was new 5000mi ago, and ran perfect for 4300mi, this problem cropped up and has gotton steadily worse in the last few hundred miles. So at last resort (should have done it first) I ran a compression check, and I had to check three times to verify the numbers I was getting. Heres what I got: Cyl No. 1: 148 2: 145 3: 126 4: 189 5 : 149 6 : 148 So I got one really high, and one really low (the two middle cylinders). 1) can anyone with a service manual for 1986 tell me what the compression is supposed to be, I don't have GM manual for that year (or anything beyon '84 before this engine was offered), looks like generally it's supposed to be around 150 (looking at the numbers for older 6's and 8's) and 2) what's going on with one really high and one really low. I've seen low before, bad news I know, but what's up with the high?