Home › Forums › Stay Dirty Lounge › Service and Repair Questions Answered Here › 1993 f150 cuts out and looses power when warmed up and underload › 1993 f150 cuts out and looses power when warmed up and underload December 20, 2019 at 9:27 am #895551 BillyParticipant Compression test. If an intake valve is not sealing properly, that’ll give you a backfire. Also check ignition timing.