V6 tribute. Got a new IAC valve. When started cold jumped to 2200 rpm. When started hot went to 2500 rpm. Both came down to 750 rpm. Got another new valve and tried it. Started hot or cold want to 2800 rpm. Very slow to come down. While driving if I take my foot in off throttle continues on for 5 seconds before releasing. Also will not drop into overdrive. Also throws a code. The latter only with the last valve. Everything thing else has been replaced. PVC valve. All vac hoses. Etc etc. I am at a total loss. Thanks.