Hey.. i'm getting an intermittent check engine light, checked the codes, getting 25 and 26 (rich and lean) and sometimes the truck isn't running right.. It seems to happen part way thru the warmup cycle, then clears up. Truck starts good cold and goes down the road ok. as its getting up to temperature it starts stumbling and surging, then once its all the way warmed up it runs better. Another thing....when its cooler out, it idles ok, but sometimes on a warmer day when its all the way warmed up it doesn't want to idle right, and stalls.

Any ideas??? Should I Start with the 02 sensor or somewhere else? Another problem is some PO went and WELDED the 02 sensor to the exhaust pipe because they broke the studs arrrgh!!

 

i would start the o2 sensor then go from there

 

It isn't turning the check engine light on anymore, but it's still got the surge/power loss when partially warmed up... I'm gonna be putting a new 02 sensor in when my new front pipe gets here next week.. I hope it fixes it!

 

might want to also check the electrical connection as well by the O2 sensor.

 

any other ideas?? I was reading somewhere about a flapper in the MAF...should I look for this?

 

test out your fuel pressure regulator. mine was off by a couple of lbs and it gave me the same issues. also make sure your VSV is working properly. the lean issue may also be cause by carbon that's caused your egr valve to stick open. (another issue i had)

hope this helps