Both the check engine light is on, but I had a mechanic look at it and nothing appeared wrong. It went off for a few days and came back on? Any suggestions as to what my mechanic might have overlooked? Also, the TRAC OFF light is on, what does that mean?

When the CEL is lit the TRAC (tion control) system is often switched off and the warning light is lit to remind you of that fact; this may also involve the ABS (anti lock braking system). The CEL light can come on if you leave your fuel filler cap on loose, the Engine Control Unit (ECU - power control module) sees the loose cap as problem in the fuel vapour evaporative control system and switches on the CEL. Even if the cap is put on firmly it takes some time for the ECU to reset itself. Disconnecting the negative lead to the battery for five minutes is usually enough for the ECU to rest itself and remove the stored error codes.