AL SS590 M6

Background. Car worked great all last year. Added a little power, took out a little weight, changed fluids this spring and just got the car together last Friday. Wouldn't shift to 3rd at WOT at all Saturday until I let off of the go pedal. Had Sean at C.A.R.S. touch up the shift points and do a sim pull on the dyno to see if it worked OK, it did.
Went to the track at Stanton,MI last night and 2 of 5 passes it shifted.
1st pass right out of the trailer, 25 psi in the rears (new Hoosier drag radials), spun to a 1.69 60' and ran an 11.51 @ 120ish.
2nd pass after dropping the tires to 23 psi from the 27 that they had climbed to, 1.55 60' no shift to third. WTF
3rd pass after a long cool down to see if it was temp related, dropped the tires to 21 psi cold, 1.51 60' no shift to 3rd again.
So I went right from the ticket booth out onto the street and ran up to the next little town slowing and speeding up and ramming on it in 3rd to see if it was the 3-4 clutch pack going out. Pulled hard in third with no signs of slippage. On the way back I slowed to 30 a couple of times dropping the shifter into second so that it would hold second, nailed it then pushing the lever to third and it shifted fine, right when it was supposed to.
When I got back to the track I went right up and ran a pass. 1.51 60' 11.12 @ 120.73.
Let it cool down for a bit and went for pass number 5. 1.507 60' and no shift to 3rd.
Is there anything in the PCM that would cause an intermittent problem like this?
I'm thinking no and looking towards a bad 2-3 shift solenoid in the trans.

Any helpful hints will be greatly appreciated.