My 96 K1500 4x4 has about 53000 miles, a 4.3l V6 and 5 speedd. Around 27000 miles, I started having problems with the engine cutting out momentarily at mid rpms, light load. Othre symptoms:
- does not do it at all for the first 2-3 minutes after cold start.
- seems to be worse in wet weather, but does it on dry days too
- sometimes improves after driving for 20 minutes or so
- will do it at a steady speed when rpms are around 2000 to 2500
- no misfires at idle or under heavy load
- most pronounced when letting off the gas to shift, feels like the engine is cutting out, not just one cylinder, causing bucking.
- overall, there is a slight lack of power, even when the engine seems to be running smoothly
When it first happened, the truck died and was hauled to the dealer who said the injectors were bad. I didn't buy that (also didn't have the $$$) and then got feedback from the newsgroup to change rotor and distributor cap. Engine ran well for a few thousand miles then it started again. I've now replaced these parts for the fourth time and, this time, there was not much improvement.
Other things I've done, related to this or not:
- per TSB, rerouted coil wire to clear other metal parts
- replaced coil and wires
- replaced fuel pump
- replaced cat convertor (bad ignition likely killed old one - common problem per TSB)
- did a "mist" test suggested by newsgroup guru, spraying fine mist of water around hi voltage parts while engine running -> no corona observed.
Maybe unrelated... refilled cooling system and engine now runs cold (havne't replaced t-stat yet). Gauge reads about 150 when warm. Before, when coolant was low, gauge was closer to 200 and had wide temp swings. Bucking problem SEEMS to be worse with engine running cooler.
Thanks for any help!!