88 300E electrical puzzle

[John Hockin]

My 88 300E was in an accident before i bought it 6 years ago (pass side fender and doors)
The "check engine" light often comes on just after i startup and goes out within a couple of minutes. In the summer the engine appears to get super heated after a few hours on the road and then the SRS light comes on irregularily and will eventually stay on. The car electrics will also fail totally when i slow down coming off the hiway under these circumstances. The engine has always restarted.This never happens in the winter

I read an article recently that suggeetd that the ECU may be at fault - a simlar car had that diagnoisis after age and under hood heat caused the ignition leads to become brittle and short out. Could this be my problem??????
Help!
BTW how much is an ECU for an 88 300E?