I have a 1998 f150 4.6 liter engine need to know why when in park it idles fine then I put in drive and give it gas it runs rough and back fires?
I have already changed spark plugs and wires and two coil packs also changed two fuel
injectors. But first I put a new fuel filter in.
Hook up a gauge and actually measure the fuel pressure. Are there any codes in the computer or is the check engine light on? I have seen MAF sensors cause this concern but I'm still leaning toward the fuel pump. Don't spend money on either until you check it out. It could get expensive real fast and you still may not fix your truck. The other thing that comes to mind is a plugged catalytic converter. You can unbolt the exhaust and run the engine to see how it preforms.
Tried the things you said, still doing the same thing.
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