1995 Mercury Sable High Idle

1995 Mercury Sable GS 3.0L with 169,000 miles. The car shoots to 2,100 RPMs on start up (during the warmup) then settles to idle at exactly at 1,350 RPMs. The engine runs great and the idle isn't rough or surging, just too high for some reason. There are no codes present and the scanner indicates the TPS voltage is correct. I have replaced Idle Air Control valve and cleaned the MAF sensor filament all without success. All vacuum lines are good and the manifold vacuum reading is good. I suspect it could be the coolant temperature sensor but without a code, I'm tired of trying to track this issue down. I suppose it could also be the MAF being slightly faulty, enough to cause the high idle but not enough to trigger the MIL. However, I don't want to spend $150 on a new MAF just to see if it works. Are there other ways to diagnose my issue without buying new parts and finding out they don't work?