i have a 1990 350 with 373 geats, and it idles through town at about 35 - 40 mph obviously this is hard on my breaks and gas milleage. im knew to cars and only got it last summer, and after a new starter, tranny, fule pump, breaks and a complete coolant rewiring, i was just about maxed out so i had no more money, not even enough for a mechanic to twist another bolt so i left the problem unchecked. i dont think its to much but any help would be great.

 

TPI? Could be an IAC issue, or very big vacuum leak.

 

You idle at 35-40mph??
Do you even use the gas pedal to get around town, or just let the idle pull you around??
Thats insane, mine I don't think reaches 5mph at idle.
Check the idle screw, make sure no one messed with it.

 

I would say check your throttle return spring, make sure it doesn't have any kinks in it. You think 35-40 is bad, one day I had taken the air cleaner off and put it back on. Somehow I messed up the return spring. As I left for work I nailed the gas and then let off. Well, my foot was off, but my car was doing 50 mph and gaining speed. I slammed on my brakes, finally after slowing down on the shoulder, I put the car in Park and real quick turned the car off.

And for the sake of the safety of others get it fixed.

 

I'm in the same boat. My car idles the same speed and I too have 3.73 gears. I know it isn't my IAC because I watch it and my return spring on my TB unit is huge. No problem with min idle either because when I come to a stop she idles at 700rpm smooth with a little stumble. Most likely your car is running slightly rich and a lot of base timing. I know I am. The rich low rpm makes for more low end torque and the advanced timing makes the engine want to keep a high idle more torque. You should see my car, it's pathetic, I usually just give it a little gas just to get going faster than the cars behind me then I drive around the parking lots with my brake.
:lala:
Unless you burn your own eproms the only thing you can do is adjust base timing and fuel pressure. I don't advice touching either because you're probably running very strong performance wise and it would be stupid to say some $40 brake pads are worth you loosing stop light races

 

yeah that sounds exactly like my car