My 1988 GMC Suburban runs fine in Park or Neutral, can rev it until I am blue in the face. Once I put it in gear it stumbles and spits and sputters and feels like it is loading up super fast.


Any help would be greatly appreciated

Have you messed with the timing at all?
When was the last tune up?

Fuel filter too?

I gave it a major tune up when I bought it in July, spark plug, fuel filter, cap and rotor, plug wires, air filter. I just bought the last of three existing kit to rebuild my T.B.I. unit. But I have no instruction manual, because the kit is a discontinued item

Is the SES light on? Pull the codes if it is.
Double check the timing and advance (if vacuum) also.
Also make sure you have a good spark and all the wires are seated well. I had the coil wire come loose on mine once and drove me nutty.

Will try those tips this weekend and let everyone know what I find