Why would my engine light come on after 300 highway miles. on 2003 Toyota Camry

My engine light always come on after driving about 300 highway miles. After driving in town a day or two it goes back out. I got diagnostic codes, it listed so many and wasn't giving a clear answer. My car be driving fine except for a few minor problems I am aware what the problems is. I feel uneasy when I drive out of town.

Asked by for the 2003 Toyota Camry