Power issues most likely. Do the new plugs require more power? Same thing happened when i was throwin my sub and speakers in..

 

When i changed my spark plugs I used 2 extensions on my rachet and that had enough play that when i torqued them in I broke the one of the rear spark plugs.
I found out cuz it worked fine until i hit 25mph the it would start to jerk like crazy and check engine light would blink. it would go away when i slowed down.

The rear are so hard to to reach. did you try rocking the engine when you installed the rear plugs?

Good luck

 

dropped the NGK's in, drove it around acted perfect but the service engine light was still on. so I pulled the battery terminal's figuring a full reset of the ECM wouldn't hurt...it did. She's purring again, and I'm happy. Now just got to make plans on how I''m going to save the face she lost against that VW down the street when she was sick lol

 

Odds are the code would have disappeared after so many problem-free starts. But good to know she's running right again.

 

the plugs actually weren't that hard for me. But I'm used to having LESS room in my blazer's engine bay. ( 504 sitting in a whole made for a six cylinder makes things a lil close fitting)

 

but again. MUCH thanks for you're input, and pointing me in the right direction

 

Congrats on an easy fix! What plans do you have for the Monte in the future?

 

with me being in college and barely making enough at work to just get by, not a whole lot in the near future. Plus, she's the daily driver so I have to be careful what I step into. But I would definitely like to vamp up some stuff under the hood, run new exhaust, maybe boost a couple pounds and get a sportier transmission. Projector headlamps and spider L.E.D. taillights are in near future. and hopefully I can find a black leather interior to switch out with the tan cloth that I have now-which is the only thing about my car that I don't like. I'd like 20 inch rims using the same rubber (Goodyear Eagle GT-which I ADORE) but as for now money is too much of an issue to do the things I'd like