hello everyone. i have a 90 s10 blazer with a 4.3 lately it has been running poorly. bucking and surging at takeoff. a little better when reaching highway speed. slight backfiring along with buck/surging. my familly owded since new. new cat about 3 years ago. since problem started changed cap, rotor, wires, plugs and coil. need to know were to go next or if anyone has had a similar problem,
thanks for your input and let me know if u need more info

 

Take one FUEL FILTER and call us in the morning.

You missed a couple parts on your tune up list there. The PCV valve and the Fuel Filter. The filter you will find it on the driver side in the frame rail on bottom of the truck just behind the drivers door location. Takes a 5/8 and 11/16 wrench on the connectors to unhook it. It will leak a little when you undo so dont lay directly under it to take it out. Try blowing through the new one in the direction of the arrow, and then try blowing through the old one... These filters should be changed every 25,000 or so. The PCV valve wont make it run bad, but should be changed on tune ups as well. Its located on top of the valve cover.

The good news, it shouldnt cost more than 20 bucks to get them both. Let us know if it helped you out and we can go from there.