4.3/ 6 banger! Has a slight miss when I start it up! It doesn’t go away! Normal speeds are ok.But the idle is rough…What to do.Also when I kick in the passing gear the engine light blinks and then goes off…
Is the CEL light on?
Have the codes read and post back with the P0123 codes.
First thing I’d do is find your engine codes. I assume your check engine light is on according to your symptoms. this will narrow your search dramatically. When you find them, post them here in the format P0300, P0301 etc.This will give people here a better idea how to help you. If the truck is due for a tune up, you could give that a try, If it’s due, you’ve lost nothing if it doesn’t fix it. If it’s not due you are better off getting an accurate diagnosis.