Rough Idle/Stumble after new Spark Plugs

[electro992]

Replaced my plugs this past weekend with OEM Densos. Plugs were torqued to spec, no anti-sieze or di-electric grease used. Also cleaned the TB using the same procedure I have in the past. Since then, the engine has run rough at low RPMs but is fine at higher revs. At stoplights (also in P or N) the RPM needle drops everytime the engine stumbles (every 2-3 seconds), and I also have stumbling when I release my foot from the brake and through the first second or two of acceleration. Almost seems like its going to stall. It does seem like the problem is worse when my foot is on the brake - just before coming to a stop or when creeping forward at a light.

I've disconnected the battery, check and re-rechecked for disconnected vacuum hoses, and waved my propane torch around looking for leaks. Not sure how reliable this method is, given that the engine does not idle at a stable RPM to begin with. No codes have been thrown driving it everyday since last Saturday. Anyone have any thoughts what it could be?

 

[Gottagetone]

Did you check your plug gaps before installing them? Make sure the wires are seated all the way to the plugs and that the plugs are in straight. Although I don't think its the case because the truck would run extremely bad, make sure you didn't cross any of the wires.

 

[Musky]

Every time I change plugs (I havent on the 100 yet) I get the same type of problem. It seems to run great at high speeds and then at idle it acts like it wants to die. Usually by letting the vehicle idle for about 10 minutes solves the problem. I think the computer has to re-learn the correct fuel\air mixture timing. I think it takes a while for it to figure out how to make it idle at the lowest rpm possible while still keeping it smooth.

I'd let it idle for a while and see what happens.

 

[Trunk Monkey]

Check your plugs and the coil packs for a loose connection. The OEM plugs come pre gapped, so that should be fine. Check the MAF and other connections. Sometimes the truck needs to relearn, but it should only take a few start cycles and some driving.

 

[electro992]

Finally got a code for cylinder 2 misfire. Swapped out the coil pack but the behavior did not improve until I also changed the plug for that cylinder. The plug that came out already had a coating of something on it. Not sure if I somehow had a bad plug, or if the malfunctioning coil ruined the new plug.