So I figured I would ask you guys for suggestions. I recently got a 2008 Chevy cobalt lt coupe(2.2L). It has 127k miles on it and the previous own really did not take good care of it. It has lowered suspension and a cold air intake. I have already replaced the spark plugs, the air filter, the mass airflow sensor, the secondary air injection pump, cleaned the throttle body, i have put complete fuel cleaner and fuel injectors cleaner in it. And its now running fine but it still has some hesitation idling and speeding up. (The car was in pretty bad shape on the inside the air pump that I replaced was half way filled with liquid and rusted the hell out of. And the spark plugs where completely blackened and I could write my name on the throttle body with out dirty it was) what else do you guys suggested I look out? Because I don't really know what else I should work towards fixing on it. Other then maybe the fuel filter which will be a pain sense it's inside the fuel tank. And then maybe the fuel injectors. Other then that what do you guys think? Thank you for anyone that takes the time to help.