2007 ford f150 4x4 truck

5.4l V8 4x4 Standard bed with spray on liner Aftermarket pioneer deck 195,xxx miles Inside is clean Good rubber Clean title or the transmission is slipping currently. I dropped the pan changed the fluid and filter. Replaced a shift solenoid and speed sensor to no avail. No metal shavings in the pan so that's encouraging. Still trying to troubleshoot it. Sold as is $4000 obo