HELP! Sputtering at low RPM 99 GT
My 1999 Mustang GT starts to sputter at low rpms when heated up but when I go above 2.1k RPM it runs perfectly fine and under WOT you can feel a small amount of hesitation and then it goes full power flawlessly. I have tried everything I could. I have replaced spark plugs, inspected COP, got a brand new MAF, cleaned throttle body and air filter, and had it professionally scanned for misfires or anything and nothing at all came up. I have no idea what it could be and it is extremely annoying . My question is, is this problem common and do any of you know for sure what it could be.