Hi this is my first post, I'm a new used pontiac sunfire 2001 owner and I'd like to help and be helped.

Whenever I'm driving the Trac Off light will go on sometimes after 5 minutes other times after 20, after the light is on rpms will rise up to 4 thousand without shifting gears and when it shifts it kicks really hard. It has shut down 3 times but after a restart the light is off again.

Make: Pontiac
Model: Sunfire
Year: 2001
Engine: 2.2

I took scaned it at autozone and a transmission shop and the returned codes where the following:

P0122
P0420
P0742

In the transmission shop they told me that it might be the TCC Solenoid or a faulty computer, the cost for repairin the solenoid is $250 and for a faulty computer $200.

My question is if they're in the right path to solve the issue, or what do you recomend?