2008 Ford F150 XL 2wd, 5.4L, 4R75W Trans (I think). Is my dads truck. Went to leave the house one one day a few weeks ago, had to give it a abnormal amount of gas for it to move but finally went and was okay till the drive home. CEL came on with a "reduced engine power" & "transmission failure" message on the message center. Pulled codes, had a P0720 (output shaft speed censor circuit) code. After code and failure message, truck still has reverse, but has no Drive, 2nd or 1st gear, will not go regardless of rpm. Changed OSS, and OSS connector and inspected harness. All good, and CEL went off. Truck would drive in all gears, but still was correct. At times it felt like it would slip out of gear, or take alot of rpm to go into any gear. Now it's back to having no Drive, 2nd, or 1st forward gears. Reverse still perfect. BUT, I'm stumped now because even after it was "fixed", and it's back to having no forwards gears, there's no check engine light, no messages on the message center. I have no codes to read to figure out the next step to take to repair. We changed the Transmission Range Sensor, with no change. Only thing left to change would be Turbine/Input shaft speed sensor. That's our next step in a week or 2. Other than that, I'm at a loss.... Any info would be greatly appreciated it, and if I left anything out please let me know. Thank you.