Ive searched the forums for a bit and havent really found what fits my particular problem..although most are very close.

I have a 1999 F150 5.4 123.000 miles, with a horrible miss at idle and at partial throttle

What i have done so far

Checked all 8 Injector leads with strobe
all 8 Plugs ( Motorcraft)
All 8 Cops ( BWD)
ran it on a Solus Ultra comes up with misfire on Number 4
At idle i check the way the coil packs are firing 123567 and 8 are 0 to -3
Number 4 -34
However when i step on it it doesnt miss and has pretty good pickup..but it stumbles and sputters at a light or when pressing the gas to move up to speed
Right now there are no codes
There was a misfire code
a Air intake temperature code (But hasnt come back)

Compression is 128 - 133 on all cylinders

Is it possible a cam follower slipped to the side and is causing a misfire?
Any help would be appreciated

 

What do you mean you checked plugs and coils with a strobe? If compression is that close on all cylinders I would swap coil pack to a different cylinder to see if the misfire follows it. You can see if it follows with the solus. Swap the spark plug with another cylinder as well to rule that out. If the misfire follows the plug or the coil then that's your problem. If it doesn't then you have a problem with cylinder 4

 

I think you have a defective plug or COP on #4.

 

Strobe..Matco test strobe kit..they come in different size's and you hook them to the power leads to see if you have a completed circuit, and they flash like a strobe...anyway

Yes ive tried swapping the plugs and cops around...even went as far as to swap injectors.

 

Right, those are misfire monitor counts. = Mis(-) 34ct

 

I'll try one more time swapping 4 around to a known good cylinder

 

So no CEL/MIL illumination ? Have you seen any CEL blinking action? Scan it with a simple scanner if you have one. Even if you do not have a CEL on.

Disconnect the green vac line from the EGR valve, just let it hang there for a minute while the trucks running. Tap the EGR valve lightly w/screwdriver handle a few times. Any Change in idle during this procedure?

 

I will try that in the morning...if that doesnt change then i'll take off the passenger side valve cover.

 

Ok i pulled off the valve cover..all the followers are fine, even checked the cam and all valves are opening and closing..the Truck is a 2004 (4.6 W code) Not a 1999

P0171 System too lean bank 1
P0174 System too lean bank 2
P0316 Random misfire at startup
P0300 Random misfire detected
P0304 Cylinder 4 Misfire Detected
P0307 Cylinder 7 Misfire Detected

 

I know you all gave this your best try, Figured i would post the solution to the problem, Had to change the computer,The fuel injection module was bad.

 

What the hell is that? You mean the drivers ? Yea, that would be a PCM problem. Doesn't happen very often.