My4.6 l thunderbird is pulsing back an forth from 600-900 and back constantly?
It will start and drive fine but constantly pulse from 600 rpm to 900 or 1100 rpm and back
Seams to be getting worse!
Check your transmission fluid for both color and level.
Possibly throttle possition sensor
If this is an idle problem I'd suspect the IAC (Idle Air Control) valve. Unplug it. If the idle stops "hunting" replace the IAC. HTH. -Jim
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