Why is my Yukon 97 start hugging gears when it gets hot

What is your question?

Ok so when I'm driving my Yukon and it's hot the transmission starts to over heat or hug a gear then I park let it cool down ND it will go just fine . I went to a transmission shop ND they said it might be a ignition starter switch can you please help me with any suggestions

What makes this problem better or worse?

It gets worse when it's hot

How long has your 1997 GMC Yukon had this problem?

It happens every summer