So I've put plugs wires cap rotor can positioning sensor coil pcv valve and grommets on each side valve cover gaskets because it was jumpy and bucked and backfired when I got it did all this and now when I let off gas it backfires a little always when it's cold if I run it shut it off let it sit 20 mins it seems to go away sometimes any suggestions

 

Welcome to DF! I will get this moved to the appropriate section so yo9u can get some answers.

 

How many miles on it?

 

Me thinks cat and pre-cat 02 sensor.

 

Has 250 thousand I was told car been replaced when baught truck and I get no codes so I believe 02 sensors r good its only been doin it when it's cold or just start up but it'll keep doin it for a good ten-15 mins

 

How long ago where the cat/sensors replaced? The sensors have a finite life span.... Plenum been fixed?

 

i'm thinking that if it only does it when cold - it rules out O2 sensors, as they are only monitored in closed loop mode (warm) and not in open loop (cold).

250K is a lot of miles. (and you said the problem goes away - sometimes, so i think that means sometimes it does and sometimes it doesn't) i'd start by renting a compression tester at your local parts store - just to rule out major problems.

i'm not advising you throw more parts and money at it, but about the only thing you haven't replaced is crank position sensor, MAP, IAT, and coolant temp sensor. map is real expensive at about $100 new. a junk yard might be about $5 or less on that, especially a do it yourself pick-and-pull. non-oem crank sensors, for some reason that i can't understand , tend to cause more new problems than they solve old problems. coolant temp sensor is easy to check for proper operation - look at the temp gauge. IAT can be checked by a DRB tool.

true backfiring is spark fire back into the intake manifold, which indicates spark out of time, or open intake valve for any mysterious reason.

from a timing thought, i'd also think about your timing chain. the stock one is terrible, and has likely been replaced, but if yours hasn't, its likely loose as a goose and just something to consider. my 01 has an almost hidden inspection plug on the passenger side of the front of the timing cover. also - since these are computer controlled fuel injection, the timing of the fuel is a computer setting called fuel sync. if you don't know your trucks history, and if anyone has replaced, twisted, or in any way screwed with the distributor, then it could be out. any shop with an expensive DRB tool can set it correctly.

sorry - just a lot of random thoughts.

 

Ya it could be alot and thanks for responding with so much ill definitely take a look into what I can and the problem always goes away just sometimes it takes longer for it to go away I've thought it might be because of timing I did distributer cap and rotor and the sensor between cap and distributor cam sensor I believe I'm not sure about timing chain if its loose would I get these problems I'm having wouldn't it keep getting worse if it was loose and I'm gettin no codes that's what's confusing

 

What is the right section to be in to get ahold of alot of people new with this website

 

You are in the right spot for technical problems with your truck.