1991 3.0L code 12, no cell on

[RedNeckRanger]

I have a 1991 Ranger 2wd 3.0L manual that has a high idle problem. When you first start it up, it revs high for a minute like it normally would when it's cold and then drops to normal or close to it. When you start driving and push in the clutch to shift, the throttle seems to stick at whatever rpm the engine was at before shifting. It gets worse as you increase speed, like you are shifting with your foot still on the gas. I scanned for codes and had one only, which was 12-rpm out of range (high). I have checked for vacuum leaks, cleaned throttle body and made sure the linkage is not binding and that the throttle plate is closing. This still happens even if I disconnect the throttle cable and reviews the engine by hand. If I disconnect the iac, the rpm drops but is still higher than normal. If I disconnect the maf sensor it finally puts on the cel, but it keeps running. Suggestions anyone?

 

[RangerNielsen]

Does it idle at said rpm when warm? my 94 seems to occasionally idle at 15-20 when its warm when i go to shift.