Just put my 8622re back toghether from a head gasket problem. Sometimes when i go to start it the check engine light will not come on on when you frist trun the key one click forward. When it does that i can't test for codes and it will not start. When the check engine light comes on with the 1st key trun, she will start right up and idle perfect. Timing is perfect, but if you rev motor past 2500, check engine light comes on and she acts like she is missing and sputters, tries to back fire. Also when running just sitting there running for awhile, she will trun off after she gets a little warm. When all that happens the check engine light stays on dim when the key is out and truck is not running. When you go to try and check for codes the light will not come on when you turn the key forward. FSM say trun key on frist, check engine light should be on, then insert the paper clip. On here it say put jumper clip in then trun on key?????? Now if i disconnect one of the battery terminals for awhile, not 30 seconds, sometime the check engine light will come on the way it should bright when i frist turn the key on. I did get it to tell me a code and it was # 3. So i repalced the ingtor on top of the coil and switched out the ECU. DID help with the idle,but when i rev past 3000rpms she go's crazy/ The idle trys to rev up and down and it not me hitting the gas pedal. Now i have to disconnect one of the battery terminals to get it to start right and then when it shuts of or stalls out it goes back to the check engine light staying on dim all the time. When i try to check for a code when i can after terminal has been off it tells me no stored codes because i had to take the terminal off to rest it and get that check engine light to come on bright when i frist trun the key. Anyone ever had this BS problem happen to them????????

 

Never had that problem myself, but.... I would suspect a loose or faulty ground somewhere.