When my truck warms up I can shut it off and let it sit for about 15-25 minutes; then it will start, idle and run fine for about 2 minutes and then it will start misfiring again. Why does this happen? Also I can take my gas cap off without any check engine light coming on.
I think it could be the evap system because it seems like the fuel vapors build up or something allowing the fuel/air ratio to be higher at startup. I'm not quite sure but maybe the evap canister vent solenoid is bad without throwing a code.
Can someone please help me out with this? Thanks.
Work already performed:
-plugs and wires
-evap purge valve
-EGR valve and sensor
-cleaned throttle body
-fuel pump relay
-PCV valve and fixed hose
-oxygen sensor, bank 1 upstream