Well...like I said. Many times before I have ran into the same issues getting the car into timing mode. I do believe if you just rev the car to 4k and hold it there for about 5 seconds and back to idle and back to 4k and do this 3 times. Which keeps the crank steady with the needle for a good reading. Works everytime now. FSM or not...unplugging the tps doesn't always work. But try both ways...and see the differance.
You did say you're timing is at 10degrees. Is this a ga16 or an sr20. IIRC 15 degrees is OEM factory setting not 10.
Not in my case....but I'm sure someone will argue it. But I can tell you that with mine in timing mode done multiple times both on a 1999 emissions over loaded de and now ve I had the same exact problem no matter how hard I tried and ended just setting it with the tps plugged in. Set it at 18 degrees no problem and the car woke up like hell. No issues.