esanmiguel

Hello, My 02 f150 4.2 with280k feels rough while in a stop light in drive. If I move it to park or neutral it's smooth. It's like the revs go up and down hard. I've replaced the fuel filter, air filter, injectors and plugs. I replaced the plug wires about a year ago. Any ideas? Your help is appreciated. Thanks

mud avenger

is it currently cold where you live?

Old_Skl_Raptr

maybe its the fact its got 280k on it hahah! if its been 60k since the fuel filter id do that again. and check the coil packs and

JCP281

try replacing the IAC valve, a lot of times when your getting issues like that the IAC valve is mucked up and needs to be cleaned or replaced.

esanmiguel

It's about 40 degrees the coldest here in san antonio

ProZach

clean the throttle body

Lenn

Possible I/M gasket leak as well.

Best way to diagnose is a spray a can of carb cleaner (using the straw provided) around all the vacuum lines on the back of the manifold as well as where the manifold bolts down. If it idles up higher than idle speed when passing over a certain area, that'd be the site of (at least one of) your leak.

97BlueFlareside

I agree, maybe try some zmax or lucas fuel treatment in the tank to clean the carbon out of the combustion chamber and and crap in the injectors

c9night

I am having the same problem with my 01 f150 with 5.4 v8. I have done all that and I am 200 into it now. I believe it is the throttle position sensor. I haven't changed mine yet. It is around 25 at oreillys auto-parts.

cvz_finezt

my 04 does the same thing. i think it's the IAC, but it stops b4 i get to work to start diagnosing it. my boss said to tap it with a hammer and see if tht does anything, if not could be a seperate issue. not ruling out anyone else ideas, but could be a or all O2 sensors., but when it was hot here in PHX it never did tht. But the IAC are notorious for acting up in cold weather (below 55`)