ever since replacing the head gaskets and timing belt, my runner has had an erratic idle and sluggish throttle response. it fires right up, never stumbles or dies out but definitely isn't running right. no engine codes, nothing visually out of the ordinary.

I was absolutely certain that all the timing marks lined up when I replaced the timing belt, I turned the crank at least 10x to be sure. after reassembly, i timed it to 10*, 12*, 8* and it didn't have any affect on the problem. idle speed is correct. yesterday I double checked all the vacuum lines and everything looks right.

all this said and done, it is idling very erratically and is extremely sluggish out on the road (even for a 3.slow). the cap/rotor/plugs can't be more than 8k miles old and the wires are about 3k miles old. the spark plugs are the same ones from before the HG failure, they look fine so that shouldn't be a problem, right?

What I'm left wondering is could all of this be a timing issue? Those of you with the 3.0 who had a timing belt be off a tooth or two, did your truck run like this? What else could it be?

 

Throttle position sensor, possibly.

 

When you set the timing, did you have the jumper shorted?

if you're getting no change when you adjust your timing, I'd check that the plug wires are on the correct cylinders, that there is nothing obviously wrong with the distributor, and that you don't have a knock sensore code (may not throw the check engine light). pull the codes & see what you have....

 

hook: my TPS was replaced exactly 2 years ago (less than 20k mi) with a dealer part. unless this part is known to have a relative short lifespan, i doubt this is it.

rabbit: yep, ran the jumper during timing. i'll double check the spark plug wires, it has to be something right in front of my nose that i missed. how can I pull engine codes when the CEL isn't on?

 

Test and adjust the TPS, easy to do and then you will know (and possibly fix the problem):
- http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

Stored codes can be pulled any time:
- http://www.4crawler.com/4x4/CheapTri...CheckConnector

 

after reading that TPS article, i remembered that I cleaned the TB extensively with the TPS still installed, hope I didn't ruin it. I'll test and adjust it later, thanks for the tip!

 

Timing should advance as RPM rises... It's pretty simple.. Check for RPM/advance as a basic check if you still think it's timing.
Retarded timing, you'll get big EGTs.. enough to give you a glowing manifold after a highway trip.