'93 240 SX with Auto Transmission - Will not Upshift w/o letting off gas pedel

[93inHOU]

I rinsed down the engine bay on my '93 240 SX about 3 weeks ago. I did not drive the car for about 2 weeks. Now that I'm driving it again, I have to let off the gas (like driving a manual) for the car to up-shift. At freeway speeds, if the transmission downshifts, it does not want to up-shift without letting off the gas. It does it from the time I pull out of the garage with the engine cold till when I park it at work 50 miles later. I changed the fluid and filter about 1 year ago. I read from another post that a TPS Harness could be a culprit if it got wet. I'm not sure where to look though for the Harness connector that could be damp. Any suggestions would be appreciated.