My Son's 90 300E (135K) has been very reliable for over 4 years until a few days ago. He was gone for 5 days without starting the car, came back the battery was dead. Took it out and put an overnight charge on it , started right up, no problems until trying to restart after warm..car would not start. I took off the air cleaner and it refired and I managed to get it back home. Started by checking some obvious culprits, air meter valve seems to be fine, checked vacum hoses, all seem to be fine , but the breather hose is broken bad by the valve cover, have ordered a new one along with an air filter (still waiting for those to arrive), put in some techron, topped off tank, still having warm start issues. Again, removing air filter allows restart back to home, any correlation there? No cold start issues whatsoever and car runs as smooth as ever.

Before throwing $$$ at the usual suspects, does anyone have some ideas on how the battery issue might have caused this problem to appear. Maybe I bumped the OVP on removal and install of the battery or caused a short to some other component, (no CEL or abs light). I'm thinking temp. sensor first, but any ideas are welcome...