Just got the motor back in with a fresh head job. Motor ran great last night. Was going to the store this morning and the cel light starts flashing. Take it back home and read the codes which are misfiring and o2 issues. Checked wires and reset codes. Drove around the neighborhood for 20 mins and not a hick-up. Later went to drive it and again the cel starts flashing. Same codes with another cyl misfire added to the equation.

 

what were the codes?

 

So, give us the code number so we can try and help you.

 

please note that some codes have to occur on multiple drive cycles, so they can be cleared, then come back in a day or two. Helps to know the number. Auto parts stores will read codes for free usually, many will not reset them. Always write down the numbers, not their scanner text conversion.

 

1129, 0155, 0135, 0302, 0304, 0306, 0308, 0300. Truck sat for over 6 months with almost a full tank.

 

P1129 - front O2 sensors swapped (wiring plugs) - ECU may be fooled by other conditions.

P0155 - O2 sensor bank 2 front wiring not connected or malfunction (short/open)

P0135 - O2 sensor bank 1 front short/open

Resolve O2 sensor issues (wiring faults, rodent chewed, corrosion in connectors).

Others are misfire, check for garden variety issues like bad plugs or spark plug wires. Original wires tend to crack with age, even if truck is parked. Sometimes the cracks are large enough that arcs can be seen if idling with hood up in total darkness.

 

I have new wires, new ign coils, and plugs. Just confused why it had issues, then ran like a champ then had issues... Almost wonder if theres a wire harness issue or if the gas is bad now. Oh, all o2 sensors are new as well.

 

The O2 sensors may be new, but the ECU can't see them connected. So start with connectors, inspecting, cleaning, etc. If you have a scanner that shows live data the O2 sensor readings should be changing, not a single continuous voltage. As for harness, sometimes a "rub" or "skinned wire" can be grounding out and seem to have a mind of it's own. Shake the harness or poke with a stick. Gas can go stale, or have water from condensation, there are parts store products to pour in the tank that combine with water to make it burn off. They contain isopropyl alcohol.

 

Alright, appreciate the help.

 

Update:
Well, i cleaned the maf with maf cleaner, put a bottle of seafoam in the gas and drove her all over today without a glitch. Hopeing it continues.

Any suggestions on putting the seafoam in the oil? Im using 10/40