Hi, I have a 01 XLT with 170 K on it. I've searched a lot on the forums and have found the same problem as I have with one difference, mine overheats if it's hot out and I get stuck in traffic or at too many stoplights.
I have the typical problem of stuttering and hesitation. It used to be only under a load but now it's all the time. The hotter it is out the worse the problem is. I drove it all winter with a few stutters here and there but nothing too bad.
I've done some of the usual basic things. Changed plugs and wires, 4 bottles of fuel injector cleaner and a new fuel filter. Also a new thermostat.

I get codes that say "cylinder# running lean, cylinder# misfire. ( Getting different cylinder #'s, 3 and 5 mostly)

Anyone had the same problem or have any ideas where to start, maybe the fuel system? I'm wondering if the overheating and stuttering are seperate issues.

 

An air bubble in the coolant system can and will cause overheating problems. As for the misfires, you might want to look for a broken vacuum line. Also check the black rubber elbow located just below and to the left of the throttle body. You could spray some ether on the vac hoses and gasket areas to find any leaks. Your engine will rev higher if you spray it on the leak. It's really hard to tell without a code. Have you replaced your old DPFE (EGR) sensor with the updated Ford DPFE sensor? You might want to do that. The old DPFE's were recalled. Mine went bad in my '01 4.2L at about 60k miles. I've also heard that the TPS sensor can cause stuttering problems when they start to fail. It'd be a whole lot cheaper to take your truck to Autozone or any parts store to get the DTC read, than taking a stab in the dark by replacing parts.

 

Thanks! I havn't tried any of those suggestions.
I've had the Codes read four times so far.

I've always got the misfire and the running lean codes but on different cylinders.

 

If you would be kind enough to post the exact code numbers, you may get better help. The techs here want the codes, not the translation.

 

Ohhhhh, Sorry about that. :o Unfortunately I don't have any of the codes written down. I'll probably be going down again this weekend after my next round of trouble shooting.

I looked into the DPFE that Peacemaker was talking about and it's failure causes most of the problems I'm having. I'll take a look at it tomorrow.

 

Well, I reset the computer and replaced the DPFE sensor as well as the TPS. I also checked for vac leaks and found none. I drove around today and it seemed a little better but the problem is still there. The CEL has not come on yet, as soon as it does I'll get the codes and post them.
I'm going to give the MAS a cleaning tomorrow and try to get a hold of a fuel pressure tester. Maybe a compression test?

 

I have a 98 4.2 with 130,000 on it...and I had the opportunity this week to see the lower, and upper intake tracks up close. I'm having some work done.

And there was alot of build-up on the openings and the butterfly's in the intake runners. Alot... I'm thinking if that passage get's too constricted, It would not let enough Fuel mixture thru...Causing it to run lean...Just a thought.