My 89 montero swb, 4 cyl starts just fine but occasionally runs like it's down a cylinder. It will idle low, like 500, then just kinda snap outta of it. It does same thing at speed, will feel bogged down, then just kinda snap outta of it and run great. It stops after a few miles. Strange thing is the randomness. 1/2 time it will start idle normal, and drive fine. Other days, it feels down a cyl for a few moments then snaps back for a moment, then boggs down a minute or two down road. My guess is electrical, like misfire plug here and there till warm, but I never heard of that. Could be fuel pump too I guess. Thoughts? Thanks

 

plugs, leads, dizzy.
first.

 

Check or replace spark plugs and wires. Test ignition coil. Check and clean all ground connectors on the engine. Hope this helps

 

Thank for help. I identified one plug that was misfiring. Broke the plug at the threads, after soaking liquid wrench overnight! Managed to get it out with an 8 dollar extractor, did the trick, runs smooth now. Anyone have any advice on methods for safe plug removal. I think they are original on a truck with 140,000 miles. I'm terrified to remove the other three. Thanks.

 

they must be sh*t quality plugs, i have never managed to break one, not even when i was trying.

more CRC, use a breaker bar, do it on a hot engine, if that doesn't work try it on a cold engine.

-edit-
plugs should be replaced, (gapped, too) as a set.

 

Thanks, yeah, I was a little shocked it broke. I'll get back at it this weekend.