replaced wires , put di-electric grease , swap coil,replaced egr and pcv valve and tubing. what it does now is sometime when i put in in gear it feels like it stumbles at idle to 1500 rpm.what i did notice also is when the truck is idling in park and i slowly revs it she revs fine , if i step on it quikly she stumble from idle to 1500 rpm is the normal?,and do i have to re boot the computer after changing these parts even is the check engine lights never came on? the truck is a 97 f150 with a 4.6l v8, 78000 mile

 

Can't hurt to clear out the KAM. Have you checked/cleaned the MAF? Have you tried to pull codes from it even though there isn't a light? Change your fuel filter?

 

did you change out the plugs when you did the work? and did you ever clean the throttle body?

R1jester- what is the KAM?

 

KAM- Keep Alive Memory

When the battery is disconnected for a bit and then reconnected, the PCM has to relearn what certain parts are doing and how they are interacting, some times this helps to throw a code quicker which can help fix the problem faster.

 

oh alright. i know what you mean i just never seen it as "KAM".

 

yea i changed the plugs -moto craft properly gap. i changed the fuel filter,cleaned the throtle body, new maf sensor. checked for vacume leaks.is the truck suppose to fumble when its at park idling and you stomp on the gas ?

 

i also tryed to pull code with no result

 

try driving the hell out of it until the light comes on then get the code(s) checked. and did you use motorcraft wires too?

 

yea i put i first had autolite wires then swap them to motorcraft with same results . is it normal for the stumble at hard rev in park? someone told me that ford is built that way to avoind sudden takeoff/whell spin is that true?

 

No, that's not true, and that's definitely not normal. Try cleaning your IAC valve.

 

well i drove it around today , it started missing worst. finaly the check engine lights came on. took it to autozone this morning and the code ready miss fire cylinder number 4.i pulled the plug out and their was a hair line crack in the spark plug porcelin. replaced the plug and she runs fine now. the plug that was in there was only 100miles on it , it was a moto craft plug. what would cause it to crack? i didnt bang it of over tighten it etc .