i bought a 88 tbird with the 5.0 when first started it idled rough but if you tapped the gas a few times it would smooth out. i replaced the thermistat and cap rotor oil trans fluid took the iac off and sprayed it with carb cleaner. when i first started it i heard a loud knocking so i shut it off now it turns over but wont start if you hold the pedal to the floor sometimes it will sputter like its tring to but wont