Hi,
I have been experiencing loss of power in my engine for the past week. My Trac off, VSC and check engine light are all on and after some minutes driving, my check engine light blinks and stays on after that. The steering wheel shakes when i step on the brakes at a stop sign or when am driving at 45-65 mph. Autozone read my codes to be P0300, P0021, P0018 and P0031. I've had a tune up done with my spark plugs replaced and oil changed and I keep experiencing the same issues. Please Help.

Thanks Kay