Ok, I have a00 L with a 4# lower, accufab tb, 90mm mass air, cold air, 160 degree thermostat, diablo tune and exhaust. I have had these parts on for around a year with no problems. About the last week or so, there has been a "studder" feeling (kind of like a miss) when I am driving a constant speed. When I accelerate, the truck drives perfect, but when I'm driving at a steady speed (with and with out cruise) there is a little kick about every 2 min. or so. I changed the plugs to denso (had NGK) and changed the coils to Granatelli's. I also changed the fuel filter and oil to see if that would help. But, it is still there. Anyone know where to look now? I am kind stumped as to what else it could be.

Thanks in advance. I really appreciate the help.

 

There is actually alot it could be I remember a while back I went through hell diagnosing a 5.4L f-250, I was getting a misfire @ cylinder 3, I would replace the plug and it would stop skipping, after driving for a day the skip would return to go away again by replacing the spark plug. Signal was checked to coil 3 and found a weak signal. Signal checked @ pcm and was also found weak so no fault through the engine harness. Crankshaft sensor was scoped and found a dip in the crank pulse. Basically there was an issue with the crank pickup. So like I was saying...theres alot it could be. From the sound of it you might have an issue with a bad coil or a faulty fuel injector? As a reference, the older Infiniti Q45's and J30's had an injector issue and would cause a miss @ Idle/low RPM. Is it safe to assume from your post that you have replaced the plugs and all the coils after your skipping problem? Im going to assume that your problem is intermittent and not constant, ruling out a compression issue. Somtimes a cylinder with weak compression will cause a miss @ low(er) engine speed and will go away @ higher rpm. Im also going to assume that there is no check engine light on. WIth that being said... If no check engine light is on you could try taking it to a repair facility to have them scan it anyway for pending codes, if a code is present that could lead you in the right direction.

Let us know how you make out, for all I know it could be none of the above. Its sometimes hard to diagnose issues through the internet

Good luck,
Storm