jd98z28

problem: - At irregular intevals trans will not shift from 1st to 2nd, just winds itself into rev limiter. May suddenly shift after a couple of stomps on the gas, or have to park, shutoff, count to 10 or 50 depending on my temper at that time, then it will operate properly or you may have to park and sit again.
Will go for weeks without issue...

parameters - usually after sitting all night or with cool motor, trans has been flushed, filter changed, no codes thrown, speedo operates properly during no shift. 98 - Z28 120K. anyone out there got a clue??