Seeking help for 4.0 running rough when cold, fine when at temp

[JeepN]

This one's got me confused. The 98 Wrangler 4.0 runs fine when at temp, but from startup, the engine runs terrible when cold and under load. With the clutch disengaged, the engine will "free-rev" just fine when cold. In fact, that is the only way to move the Jeep before it is up to temp, by using the clutch to gain RPM's over 3,000 to get the Jeep moving. I changed the TPS a month ago due to a check engine light. There is no check engine light now and my local service tech is scratching his head too. Please help!!

[BLAZERBOY69]

Originally Posted by JeepN

This one's got me confused. The 98 Wrangler 4.0 runs fine when at temp, but from startup, the engine runs terrible when cold and under load. With the clutch disengaged, the engine will "free-rev" just fine when cold. In fact, that is the only way to move the Jeep before it is up to temp, by using the clutch to gain RPM's over 3,000 to get the Jeep moving. I changed the TPS a month ago due to a check engine light. There is no check engine light now and my local service tech is scratching his head too. Please help!!

WHEN YOU SAY "RUNS TERRIBLE", ARE WE TALKING A SHAKING, LOUD NOISES, OR WHAT? JUST FROM WHAT YOU'VE DESCRIBED ABOVE, I WOULD TELL YOU TO CHNGE YOUR FUEL FILTER

[JeepN]

When it is cold, running terrible means it does not get fuel/air, or so it seems. You press the accelerator and power is lost. Push in the clutch, and the engine revs just fine. I've been driving the Jeep like this for about 2 weeks now. I changed the cap/rotor last weekend, no help. Thinking about taking it to the dealer....I cannot wait in the mornings for my vehicle to warm up before I leave.

A fuel filter may be the cause. However, the filter is in the tank, at the inlet of the fuel feed. There is 111,000 miles on the engine. But why would it run fine when at temp??