Is it a stock carb or aftermarket, have tried adjusting it?

I would also check the timing.

Having to much O2 is still a bit odd, too bad you couldn't get a reading?


More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed