4.6 SOHC runs poorly and never enters closed loop


New Member
Apr 18, 2021
I recently replaced my manifold since it was leaking coolant into the spark plug wells causing it to run poorly, i had it sitting for a bit since i didn't have the time to fix it. After i replaced it, it ran a lot better but once the thermostat opened up it started to run poorly again. There are no DTCs and i checked the PIDs and i noticed that it stayed in open loop even after it was at operating temps and a quick test drive around the neighborhood. The ECT works fine, at Idle the RPMs jump around a bit especially when putting it in gear. It runs somewhat alright at higher speeds but around 10-40 mph it sounds like its misfiring a whole lot then smooths out after getting above 50. Does anyone have a clue on what to check?