Why does Check engine light comes on with cruise light blinking after going over 80 mph

I have a forester 2007, that has an issue when you (accidentally) go over 80.
Three times now, I hit 80 and my check engine light comes on. First it flashes
(which I know is bad but I've taken it straight to a garage before and they find
nothing wrong), until I slow down under 75mph, then as long as I don't go
over 80 again, everything returns back to normal. But, if I accidentally hit 80
again, it will flash, the cruise light will flash, then the check engine goes solid,
while the cruise continues to flash. Sometimes this is after filling up with gas
and long road trips. Nobody has been able to figure out why, although The
lights remain on until it is reset. Any of this make sense? Thanks so much!