2001 Dodge Stratus running poorly

Hi. 2001 Dodge Stratus.A little over 100,000 miles on it. Brought it in for tire replacement, and also heat was blowing cold air. We were told H2O pump was going and timing belt should be changed. After timing belt and H2O pump fixed, the car was running extremely poorly at low idle speed, and in park. At times it would just die at a low idle (like when slowing down to take a turn). It runs fine at regular speed, it's just when it's in park and when the rpms' drop to or below 1. We had the mechanic check the timing belt, he says it s fine, also ran a compression cylinder test (something likethat) and it was 175 across the board; he said that was good. A friend of his who works for a Dodge dealer said it could be that either the O2 sensor or the cam sensor might be no good. Your thoughts on this? We have been w/out this car for about 3 weeks now. I am extremely frustrated! Thanks for any advice/help.