1999 Pontiac Grand Am; 160,000 miles; 2.4 liter engine. My car is having an issue where it idles rough, emits a high belt squeeking noise during idle only, and stalls out constantly if coasting. Also, the car is extremely hesitate when I press on the gas pedal and 90% of the time I have to push it to the floor or else it will die. So far I have done the following: no codes on a testing unit at an auto parts store, coolant sensor tested and good, and cleaned IAC Valve with Carb cleaner. I only did these as word of advice from people, I myself don't know much about cars. My car has stalled out on the middle of the freeway more than once and I am afriad I am going to get myself or someone killed if I don't find out how to fix this. And I don't have the money to take it to get looked at (i'm a college student). ANY advice on this would be great. Thank you!