Found out....And it isn't pretty....

I've got a coolant leak inside the body which would explain why it has become more of a problem on the highway. Makes me cringe to know all that coolant was being forced into the cylinders and wreaking havoc, And you all know that blows..Glad it was caught now and not after the engine seized up. And the engine light did finally come on, flashing like crazy. That's when I knew it was time to go right to the shop and have it torn apart. She'll be fixed this week

Thankx for all the suggestions guy's....only wish it had been one of them.