Just recently I had my engine light plus the VSC light come on. When I took it to a local repair shop (ETD) they couldn't decipher the coding. There were no symptoms at the time. When I picked up the car the two lights were on. The next day I noticed that the lights no longer were lit. Two weeks later I'm driving along after a 30 mile ride on the highway and when I get off the highway, the car is idling high, lunging forward at stop signs while I force down the brake pedal to keep the car in place. When I put the car into park, the RPM needle goes up and down (a range of at least 1000 rpm). The idle in neutral is around 1250 rpm. When I started the car up later, it's not as bad, but the car sounded like a truck. Then, the other day, I'm backing out of the driveway and the car stalls. It took a lot of coaxing and holding down the gas pedal to get it where I could continue to back out and not stall. On Saturday, I took the car in and they found that a gasket in the exhaust system had failed and replaced it. The car sounded and performed so much better. I'm thinking it's all fixed. This morning, the high idle returned with the car lunging and the minimum idle at 1250 rpm. Where do I start? All ideas are appreciated.

TPS motor on intake manifold.