1999 Subaru Legacy L Wagon 2.2 30th Anniversary-Transmission

Transmission does not hold 4th gear at all, just immediately pops out and can not be held in place, so I have to go directly into 5th when reaching over 40 mph, occasionally, not always, pops out of 3rd and 5th, but pops right back in, rarely, 3rd and 5th pop out when letting off of gas pedal, and more rarely, slips out of 3rd all on its own when giving it gas, but does pop right back in. There is a slight noise at times, but not always, almost like something is being dragged, in 1st and 2nd only, and the shifter makes a grinding noise sometimes, but not always when switching into 3rd and 5th. The shifter is very loose with tons of play and makes noises from shaking and vibrating. Holding the shifter in place with my hand eliminates most or all of the rattling and shaking noises. Mechanic said it was my clutch and flywheel, replacing both with absolutely no improvement at all. Wouldnt know or think it had a new clutch or flywheel. Fluid is full and changed, and said there was some small metal in old fluid. Car/transmission does run strong otherwise. Is it my transmission or something in my shifter, or both? Thank you very much.