Idle circuit problem with new engine
 

I cracked the block in my 1992 F-150 302 manual NITE. I bought a long block from autozone. I had the engine installed at a local exxon. I didn't have the time or space to do it myself. The main problem I am having is the idle. When I turn on the ac, the idle should pick up a little to compensate for the extra strain just like it used to with the old motor. Now, it drags the motor down very low. I'm amazed it keeps running at that low rpm. I took it back and found out the negative cable to the engine wasn't connected at all and the chassis to engine strap was loose! How it ran at all, I don't know. Anyway, it fried my stereo amp in the process and it still wouldn't idle right. I left it with them and told them to call me when it was ready. I have it back now. They raised the idle to compensate. The temp sensor for the gauge was bad and I replaced it and the other sensor also just in case. I probably need to replace the O2 sensor but, haven't had the chance yet. It's running better but, when I push in the clutch, the engine is revving and makes for rough shifts. Oh, I had to put in new fittings on the throttle body for the coolant. The old one blew apart on the way home. I removed all the sensors and cleaned the throttle body thoroughly before putting it back together.Does anyone know what I can do to make it idle right? I think it has the MAP sensor? It has the twin opening throttle body with the huge intake that hangs over the valve cover. Thanks in advance!

Idle circuit problem with new engine
 

Am I alone here? Anybody?

Idle circuit problem with new engine
 

I have just replaced a 302 in my 1990 f150 4x4 I'm having a similar problem at idle. when I try and start the truck it will go to 1100rpms or so and then drop to 400 and die. I can start it by giving it a little gas and it does fine. I also have a slight miss under power not bad but noticable. I will be checking the idle air valve tonight it stuck on me once before and the symptoms were the same. I will write back and give you an update. Did you notice any improvment when you hooked up the engine ground strap? I forgot to connect mine and was curious if that helped you any. GOOD LUCK!!!!!!!!!!

Idle circuit problem with new engine
 

by the way I'm not sure if it is called an idle air valvle but it is located on the drivers side of the intake by the throttle body. it has a rectangular plug (black plug and orange and white wires i think)
when i cleaned it last time i removed the electric solenoid from it and used carb claner to free up the needle on the inside of the valve. My wifes 302 explorer also had the same problem a couple of months ago i cleaned the valve and it was fine. Be sure to let me know what you find out!

Idle circuit problem with new engine
 

Thanks for the input! I have a very hectic weekend (friend's wedding) and I doubt I will be able to check it out until next week. I will post my findings though.

Idle circuit problem with new engine
 

Well, I think I have the problem fixed. The first thing I did was replace the o2 sensor. How are the wires usually routed? Mine were between the manifold and engine bracket and the connector had melted together. It was a pain getting it apart. I rerouted it under the bracket and will have to do the same to the starter cable also when I get the time. Anyway, I also pulled the idle valve and cleaned it although, it was moving easily. I also noticed the return springs weren't pulling back properly so, I added a light spring. So far, it is working great and idling much better. I'm sure the o2 sensor was a big problem but, I think the spring was the biggest help.

Idle circuit problem with new engine