97' f150 4.2 v6 misfire

[IMenriched]

A friends has this intermittent miss/misfire on his 97 f150 with 4.2v6.

history:
earlier this summer a scan showed a misfire on #4 cylinder (code p0304)...he took to a repair shop and discovered that there was a leaking head gasket, which explained some missing coolant every once in while.
To fix, the heads were removed checked , planned and new injector on #4 cylinder, new plugs and wires ...to the tune of +$1500......and more recently coil pac.

he still has this intermittent miss/ misfire..not really happy, nor anxious to spend more.

tried to help him out and ran codes with my cheap scanner....after it finally tripped the CEL on the dash....came up with...you guessed it....misfire on #4 cylinder. After digging thru the scanner menu a bit, it did show the at 3 of the 8 precheck came up incomplete.....those missing are, evap sys, O2 sensor, and O2 sensor heater. we did give the MAF sensor a quick spray with some cleaner. didn't help.
he mentioned that it seems to be worse as weather cools and cold starts....but not consistantly holding true to that, as it will still miss fire when fully warm.

surprised that with all the work previously done that new O2 sensors were not replaced....so tried to encourge him to return it to the place that did the initial work & show the missing systems check...see if they can narrow the options.

thought I'd post this here to see if others have run on to this and might give some direction to the cure.

thanks in advance

 

[fordo66]

'97 f150 4.2 v6 #5 misfire

I love ur screen name IMENRICHED it's cool to speak with fellow christian! Anyway My next door neighbor is having simular issues and I was blown away by all of the problems with misfiring with the 4.2 ,6, and 5.4L engines. We are working together on the problem with his 4.2 v6 misfire on #5 code 0305. # 5 is the only issue no other codes. So far we replaced the plug wires which were completely gone and plugs but still had the issue so I checked the output of the coils with my tester and all seemed well so I did and ohms check on it but nothing slapped me in the face there either. We went ahead and replaced the injector to no avail. WHAT TO DO!
My scanner' live data shows to o2's working good exhaust smells normal nothing rank MAF is responding normally I'm now leaning toward the coil pack I think it might be breaking down.

Any thoughts?

 

[mentalbreakdown00]

yes on the 4,2's the balancer is bad about spinning the outer ring where the CKP sensor ring is, making it fire at the wrong time, seen it on at least a dozen truck over the last few months. May not be your exact prob, but be worth checking