03 1500 Hd

[deaf electrician]

I recently bought a 2003 1500hd with 110k mi. The truck has 3.73 gears and 6.0 engine. The problems I am having are horrible gas mileage which i think are caused be a high idle when in drive and the torque converter clutch not engaging. The truck idles in drive at just over 1000rpm and will drive itself and shift into second with out pushing on the gas. I also think the truck is driving at too high of rpm while cruising. At 70 mph I am at 2500 rpm. Also there doesnt seem to be much of a drop in rpms from 3rd to drive only a couple hundred rpms.

 

Does anyone know if this is caused be the tps being off or the torque clutch converter wearing out. Or something else? I have changed the plugs and wires. New air filter. removed and cleaned the maf sensor and throttle body and replaced fuel filter. any help would be appreciated. Thanks Eric

[2016 Sierra Owner]

What gas mileage are you getting? I had an 01 2500 hd and got 11-12 city and about 14-15 hwy. That's about tops from what your going to get. Mine had the 6.0L and 4.10 gears.

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I got basicly the same truck with 4.10 and at 70 I'm around 2300 rpm. My truck will take off by itself also, it will shift into second then third assuming it's on flat ground. But, it idles at about 650 rpm in drive at a stop sign.