Hey guys,

I have a 1996 GMC Jimmy 4dr 4x4 with that wonderful 4.3 in it. To start, it has a new fuel pump, new fuel filter, new plugs, new wires, new cap and rotor. When it hits about 70 mph, the thing starts bucking a little bit. Watching the tach I can see it jumping a bit when it does this. Feels almost like a misfire. On the other hand, I am getting 19-20 mpg flatland highway mileage (adjusted for the fact that I drive up and down a mountain every day I go to work) which is better than the 17 it was getting. I just don't think I can handle it messing up like this. Any thoughts/suggestions? Anybody living in East Tennessee that would like to take a drive with me to get thoughts/suggestions? Until my Honda is fixed (requiring a new motor) this thing has to be my commuter and my fire vehicle (it was bought to be the latter and my oh crap it has snowed and iced on the mountain vehicle).

P.S.- My phone crapped out on me last night. As soon as the new phone gets here I will have pics of the Strugglebuggy up.

 

Any ideas folks? Any input would be greatly appreciated.

 

Are there any trouble codes?

 

Did you use Delco parts for the distributor cap, rotor, plugs?
How old is the ignition module?

 

Dirty Mass Air Flow Sensor? Maybe check throttle Position Sensor.