1998 Jeep Cherokee check engine light goes off when gas tan

Engine Performance problem
1998 Jeep Cherokee V8 Automatic

My Jeep Grand Cherokee has 148,000 miles. It has only had two owners -my father and myself. It has never had any major problems -very dependable. About a month ago, the check engine light came on. I had the codes checked and they came up as the transmission solenoids. But before repairing them, the check engine light went off. I hadn't been driving it as much (maybe once a week) so I figured maybe it just needed to be driven on the highway more.

Here's the thing I've noticed -when the gas tank is completely full and the tires completely balanced, the light stays off. One the gas tank gets to about 3/4 full, the light comes on again. When the check engine light is on, the car accelerates sluggishly but once it's over 35 mph, it runs fine. When the check engine light is off, the vehicle runs perfectly.

Do you think this could be related to the solenoids or could something else be giving a misreading? I appreciate any help you can give me!!

Thanks for your help!