Buggy Auto Trans

[JHServin]

Well the car is a 1990 2-Seater NA. I can take it out for a drive and everything runs fine no problem, but lets say 1 out of 10 of those daily drives the transmission decides to shift only at 4k rpm and really hard. It does that the rest of the drive, unless I pull over and turn it off then back on. When I do, and put it in ignition the auto trans lamp on the dash flashes 1 long flash followed by 15 short flashes. So I take the key out and put it back in until the lamp does not flash on start up then everything is fine again. Anyone out there know what the problem is? Usually I'd take suggestions and try them out, but I currently don't have time to mess with the car like that, so I would just like a straight answer please. If not then I'll just wait until my mechanic is free and have him deal with it. Thanks in advance.

[300ZXttZMAN]

Moved to Z32 Tech section.

Shadow topic left in place.