This is for the old '99 that the parents have now. It's got a "miss" at idle............but only after the engine has gotten up to operating temp. Cold idle is normal with no miss. It's a miss, but the computer adjusts by increasing the idle speed slightly after warm up.. Running up and down the road, she runs as good as ever. Dad says she's been averaging 19mpg most every fill up. What should I look for and check to diagnose this??? Thanks guys!!