My 94 C3500 454 idles around 1300 RPM in park but drops down to 1000 in drive. Before replacing the map sensor it idled around 14 or 1500. The truck also has a miss you can feel when idling but its not apparent when driving. It accelerates fairly quick and seems to have good power but does seem to lag for a second when I get on the gas before it takes off.

I have replaced the egr valve, map sensor, fuel filter, spark plugs, and wires. The map sensor is the only thing that seemed to make a difference as it dropped the idle a little.

The truck seems sluggish on hills when towing a 4600 pound trailer and is where I can feel like power is lost somewhere.

For comparison, I have a 2004 Dodge Dakota with a 4.7 that handles the same hills with the same trailer just as good if not better. I would think the big block should out pull the Dakota. I have only owned the truck for three months so I'm unsure of how it normally runs. Any ideas or help is appreciated.

 

Don’t know that engine, but first two things I’d check are fuel pressure and for codes (some don’t cause CEL).

 

Sometimes a vacuum leak can cause a high idle and the problem disappears with increased RPM.

 

The first place I'd look is the tbi gasket. It's a common problem causing the high idle. You can spray some starter fluid or carb cleaner to check it. Replacing mine dropped the idle from 1400 to 900.