It straightening out it doesn't do this all the time.
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1999 Ford F-250 Super Duty Question: My truck runs great until it gets into a hard pull.then it starts splutting .
DonziGT230 July 01, 2014, 20:21Journeyman
Check fuel pressure under load if you can. If the fuel filter hasn't been replaced recently you could try that, it sounds like a fuel supply issue.
Answer #2Katzman Automotive from Katzman Automotive & Transmissions, July 11, 2014, 13:23Technician
Is the check engine light flashing on and off when this is happening? If it is, then you have a serious misfire. If the check engine light is on, but not flashing, it could still be a misfire or something else like a fuel issue, but you should get the codes scanned to point you in the right direction.