high idle check for vacuum leaks first check all fittings into the intake and especially the pcv hose oil goes through them and right about the mileage to have em start rotting out. Listen for whistling under the hood at idle, if you cant pinpoint then get some starting fluid, carb/brake cleaner and spray around all the hoses and listen for the idle to raise or lower.
if no luck there you might have to get it to someone with a scanner so they can check the tps voltage. the hard shifts are from the high idle, fix that and your gear engagement will feel much better