1995 truck will not run when warmed up

[hart1]

I have a 1995 pick-up with a 3.0 L v6. My problems started about 2 weeks ago with a bad plug wire. It ran fairly well for a few days, with only a minor skip. Then I got into town one day and as the temparature increased the worse the engine ran. I pulled off of the road, barely, and noticed the smellof something burning. I crawled under the truck and noticed the cat-conv.was red hot. I alowed the engine to cool for 1/2 hour and it ran fine for therest of the way home. So i replaced the plugs, cap, and wires, and gutted the cat. It ran like new until it reached a certain temp. then began to lurch and jerk like before. I was told the o2 sensor may be bad, so i disconectedit, with no change in symptoms. I have not had a check engine light, and am wondering if anyone has suggestions. thanks for the help, Please.

[elwesso]

Very weird. is the truck overheating? does it seem to get hotter than usual? Weird things happen when they get too hot and the computer isnt sure what to do...

I would personally lean toward something MAF related... You might check the MAF connector for corrosion and consider picking upa used MAF. Most of the time when nissan MAF fail they fail in such a way that they give a false but still "acceptable" by the ECU. Hence, they wont throw a CEL.

[hart1]

No, the temp. gauge has always remained in the normal range. It does seem to run a little better since i disconnected the o2 sensor. Now it runs very well when cold and runs well at low rpm even when warm. I am thinking maybe it is going into some form of limp mode. Although I am by no means sure. It idles fine and runs to about 2000 rpm. Anything over 2000 and it dies. By the way this truck has 198k miles, and this is the first problems I have ever had.
Modified by hart1 at 6:00 PM 5/17/2007

[elwesso]

The catalytic convertor was red hot you say? LIke actually glowing or what? If it was actually glowing red I'd say you have a clogged catalytic convertor. The clogging could also be causing your driveability problems.

He mentioned that he gutted the cat.

[hart1]

I have now changed o2 sensor, and coolant sensor. There is no change.I have noticed with the weather that this problem is very temp. sensitive.I was wondering if anything in the ignition could be affected by the airtemp. The problem seems worse and takes longer to clear up based onhigher temps. I am leaning toward ignition problems because when it starts running erraticly the tach goes crazy and it just seems like it has no spark. When it gets to a certain temp. it will not start at all. But when it cools down completely it again runs fine.

[hart1]

I am out of ideas, and cash. I have replaced the coil and the ignition modulewith no change in symptoms. I don't want to buy a maf sensor unless I amsure. Can I disconnect this sensor and drive to see if this is the culprit? Also is there any way to fool the computer into thinking the engine is coolto keep it in a closed loop, or whatever mode it is in when it is cool and running well?

[Bwana]

You could try cleaning the MAF and the MAF plug to see if that helps. It's sounding more and more like a MAF problem, but it's tough to be sure.