I bought my 97 Talon ESI a couple of weeks ago. When I test drove it, the check engine light was on and the dealer said it needed a new air filter. Air filter installed and bingo, the light was gone. This morning in came back on, I checked my oil my coolant,...not too sure about the transaxle fluid, but I checked that too. What should I look for now?, what to check, adjust...etc? If I just go get a tune-up, which I was planning to do, then should this problem be fixed???