I have a 1999 E320 4-matic wagon (124k miles) that has provided very reliable service until this past week, when we had a heat wave. I had driven it about 8 miles to a store and parked it in a hot (103 deg) parking lot. When I came out 30 minutes later it wouldn't start. After several attempts and about 10 minutes, it started and I drove it home without incident (no CEL showing). The next day, also very hot, I drove it 5 miles to the post office. Once again, when I came out after 15 minutes, it wouldn't start. After several attempts, and 20 minutes, it started, so I tried to get it home. This time it stopped after 3 miles, so I had to be towed home. Now it starts fine (when cold), and I'm preparing to dig into it to find the "heat" problem. I first pulled the connector off the crankshaft position sender and hit the starter. It replicated exactly what had happened when I tried to start it hot. I'd appreciate any thoughts on similar experiences, the CPS, and any other likely candidates. Thanks.