2000 Silverado with 4.3 engine. Check engine light illuminated. Code says "random intermittent cylinder misfire". New plugs, (OEM) new wires, new rotor, new cap, new cam sensor,
new fuel filter...approximately 4,000 miles ago. Engine has no power, runs bad & gas mileage has decreased dramatically.
Any ideas?

 

injector maybe, based on what you've done so far. What was the code specifically do you know?

 

I don't know the exact code. The code translation was: Intermittent random cylinder misfire. I don't think it is an injector since the code implies that the misfire is not just one cylinder, but all cylinders randomly unless I'm reading more into the code than what it means.

 

P0300 (Random/Multiple Cylinder Misfire Detected), maybe? How was it running before the tune-up? If unburned fuel were being dumped, the catalytic converter could be toast (melted, fused) and restricting the exhaust flow. That could create the kind of bogging down, running rich symptom.

 

The truck ran good after the tune-up for about 3,000 - 4,000 miles. Like most of the 4.3 motors it is/was not a power house. Just recently started running bad at highway cruising speeds (70 mph). At WOT it does not miss, stumble or anything but accelerate. Around town slow speeds there does not appear to be a problem---only at highway cruise speeds is there a noticeable miss or "chugging" sensation. Put in a bottle of TECHRON INJECTOR CLEANER today. Maybe that will help. I'm open for suggestions.

 

Hope that takes care of the problem. If not, see if you can post the freeze frame data to go with the trouble code next time.