I have a 1995 ford thunderbird 3.8 l. I changed the heads acording to a chilton book. The car ran well for approximatley 2 weeks and all of a sudden it started Idling high. I turned the idle screw all the way off and no change. any help would be deeply appreciated with gas prices these days.

Check for vacuum leaks (cracked hoses, hoses that are disconnected, brake booster). With the engine running, spray some WD-40 around the top of the engine near any vacuum lines and see if the idle speed changes.

i had a high idle at times in my 1989 TBird that is also a 3.8. My mechanic found a broken EGR hose and he said that maybe the reason for the high idle. After fixing that, it hasnt had the high idle since.....

good its fixed...the other thing it could be is an idle air controller. That happened to me once...

I have a 1995 ford thunderbird 3.8 l. I changed the heads acording to a chilton book. The car ran well for approximatley 2 weeks and all of a sudden it started Idling high. I turned the idle screw all the way off and no change. any help would be deeply appreciated with gas prices these days.
It sounds like you need to replace your IAC. (mounted on top of the throttle body).

To check it, remove the wire connector and turn it 180 degrees and replace the screws. The wires will NOT reach so dont try to plug it back in.

Start the car and it should return to base idle.