I have a 2008 Ram 1500 4x4 with the Hemi engine (~58,000 miles) that seems to be running poorly and sluggishly. My '01 Ram work truck is dead (I think it needs a new PCM) so I have been driving my '08 every day as my work vehicle and have put more miles on it in the past 3 months than I did in the previous 12. It seems to hesitate on acceleration at times, and it seems to drive differently almost every day. Some days are OK, other days it seems like something is seriously wrong.

However, no codes have thrown yet. I did have it serviced recently to fix an AC issue, and the fuse box in the engine compartment was replaced (supposedly it had shorted and was causing the AC fan to run continuously instead of cycling on and off). After that was replaced, the truck ran GREAT for 2-3 days, and then started driving like a dog again. It could be coincidence, or perhaps somehow the AC repair was related to the improved performance.

Anyhow, I have been monitoring the engine with my scanner, and a few things seem out of whack. The main concern is that the engine load reads 20% - 35% at IDLE, which seems extremely high. The truck has done this for as long as I've had the scanner, but the reading seems even higher recently. I suspect a vacuum leak or MAP sensor/TPS problem, or perhaps a clogged catalytic converter, but I was wondering if any other Hemi Ram owners could provide typical readings for the following data at idle:

-Engine Load
-Throttle position
-Intake manifold pressure
-RPM

Also, can anyone tell me what the engine vacuum should read at idle? I'd like to put a vacuum gauge on it this weekend to see what it reads.

The voltage also seems to fluctuate frequently, and I wonder about an alternator problem (perhaps the alternator is failing and causing additional drag on the engine?), but I'd like to rule out a vacuum/intake problem first.

Any help would be much appreciated!