I have a 1989 jimmy 4.3 4X4 with 176,000 miles just tuned up. It runs great but when you get on the highway it has no power, almost to the floor at 70 miles an hour. Has been getting worse but got really bad when i changed the harmonic balancer yesterday.Any suggestions would be helpful

I have had that problem, SES Light on? Could be a plugged cat........... Thats what mine was, I dont have ET so I just hollowed it out, it doesnt sound to bad, but I would suggest replaceing if that the problem...

paxfam1

mine is already hollowed out got it that way with a flowmaster behind it

Think the fuel filter might be clogged up?

check your timing......................................

Just changed the fuel filter a couple months ago while changing the fuel pump but il throw another on and see what it does and il check timing 2maro thanks guys