I have done the smoke test for a vacum leak , tested or changes all spark plugs, wires, coil packs and injectors, cleaned the o2 sensors with gas and a vibrating massager, run seafoam through the intake and has tank, still a code.

the engine ran fine until i got exhaust leaks on both manifolds fixed. Then the p0300 code pipes up. Since I have cleaned the o2 sensors, now the lean codes show up. The engine seams to run fine at higher speeds, but smells extewmely rich, even in the cab.

the only weird thing I have noticed is the engine runs better with the pcv line disconncted. Please help.

 

This is a 6.0 liter h2. I have also cleaned the sthottlw body and maf sensor and air filter

 

Went through this recently. Grabbed a can of carb cleaner started spraying from source of course fresh air intake.
-bellow to MAF was leaking, replaced.
-Rubber hose to Evap Solenoid leaking replaced
-Stopper above that connections slight leak.
-Frt of Supercharger intake small leak. Re torqued all intake bolts. Sprayed rear lines vacuum brake, pvc dummy line, and everything else. GOOD.

It was Still missing on start up.
Cleaned MAF contact cleaner, same.
Immediately remember that it runs fine when warm, meaning it was in closed loop running off O2 sensors with ECT.
-Replaced ECT(Coolant Temp Sensor Drivers Side Frt of block 2 wire connector)in morning after letting it cool off for the night. Pulled power off battery after install to clear engine light. Fired up truck F#$kn Mint.

 

just noticed this thread is from 2018

Neal