I have a 98 Hyundai Elantra with Trans problems. When it rains for a couple days the

[Mag]

reverse goes out.? If it rains for more then a day and heavy my reverse in my Automatic trans slowly starts going out. It will go when idling but once I hit the throttle it will not move(like its in neutral). After the rain stops and it takes a day or two to dry out it is fine. Anyone have any idea what is going on?
I have checked the fluid, Hot and Cold. No differents. Also had the trans flushed and filter changed a month ago. Still havin the problem.

[NEWBEE1]

Check your transmission fluid level, the radiator cools the fluid to the Transmission. Rain will tend to cool the engine more than mormal. When dry the fluid level will rise do to heat. You can try to change the transmission filter too.

Good Luck