Questions on 1997 Mitsubishi mirage

Hi
I am planning to buy a 1997 Mitsubishi Mirage with Auto transmission. But the car has 2 problems.
First problem is that the "Check engine" light is ON. The current owner is saying that the problem is bcos of the Exhaust gas recirculation (EGR) valve and it has to be replaced. My question is that, could that be the only reason why u could have "Check engine" light ON.
Second problem is that the when the car shifts gear internally, u can feel the jerk in the transmission. Is it normal for these cars or is it a sign of impending failure.

Thank you,

first question:

Try resetting the ECU by removing the ECU fuse... the 40amp fuse in the engine bay and reinstall that ECU after about 10 sec.. This hopefully will clear all errors saved in the ECU.

Question 2:

When the car changes gear, what is the rpm and which gear was it? normally it would not jerk.

Yo

I drive a 97 mirage de automatic and im the worlds biggest led foot. if im all over the gas my tranny slams too. the check engine light could be a few things, like when i put my subs in i disconnected my battery and that made my light come on until the car reset the diagnostics. there are a lot of things. my best advice is to take it to mitsu and have them look at it but thats expensive.