It has happened twice in the last 2 days. I have to find the problem before my maggie install. Well my truck is an 04 ec silverado with 5.3 and 45xxx miles. I just put pacesetter long tubes and ORY pipe with full exhaust and Cold air intake 2 weeks ago. I had issues with it and it was the spark plugs and o2 sensors were replaced. Ran beautiful for two weeks now yesterday on my way home it started to bogg real bad about 35 mph and wanted to shut off on me. I tried to give it gas making the problem worse. I had to pull over shut off truck and start it and it ran fine. The truck is not tuend yet and the rear o2 sensors are unplugged. What am i missing fron o2 are new and new plugs. no leaks on the intake checked that. plug wires are intact checked those no rubbing on the wires. Can it be it needs a tune. And by the way my gas milage is worse than a hummer H2 with a twin turbo im saying its like 9 miles per gallon. need some advise. Im going to work will let you know if it happens again. going to check for loose plug wires again.

 

I'd say check your fuel pressure first, then check your exhaust backpressure. Could be a weak pump or a clogged cat.

 

I think you are getting an exhaust leak pre primary O2 causing the PCM to dump fuel, fouling your plugs /O2s and giving you poor fuel ecomomy. Pull a plug and look at it. Better yet, scan the PCM and pull any codes, monitor your fuel trims. Just a random guess based on the info you posted...

 

that sounds like the fuel pump

 

I have no cats it cant be clogged cats I was thinking it might be no enough back pressure its a 5.3 with long tubes off road y pipe and full exhaust. the fuel pump and filter will be changed with the maggie install and the plugs will be re done to tr6's

 

I think its running pig rich i may need to get a dyno tune.

 

yep, it's either fuel pump failing or screwed front o2's. The only sign that my fuel pump was about to die was the 1-2 weeks before hand I was getting single digit gas mileage.

 

Were the plugs fouled when you removed them? Could be running rich...is the air intake tube tight, and how about the MAF, is it covered in oil from the air filter...just some easy things to check before you get too deep into it...

 

need to check the MAF the intake is new and was very oily maybe thats it.

 

Update: It only does it when the engine is cold when its up to temperature it stops. I'm thinking its running so rich the plugs are fouling up. Going to check them I may hold off and replace the tr5 with the tr6 when i do the maggie install. What gap are you guys running your plugs at I was told by auto zone. .40 and a tuner said .35 if going to FI.