I recently bought a 91 Camry LE 156K miles, 4 cyl. It worked great on the test drive. Yesterday I drove it for ~50Miles and 3 times during the trip it momentarily lost power (tach went to 0 and check engine light came one) for several seconds. It then came back to life like nothing happened. This happened at while on the highway so I was coasting until it restarted. I don't remember hitting any bumps to cause this to happen. Any thoughts?