Hi new to the forums, I just bought an 05 Mustang GT with about 85k miles on it. After owning it for a month I decided to take a look at the air filter (dirty) and decided while at Walmart just grab a cheap one to get some cleaner air into the engine before I get a cold air intake(hopefully coming soon). However since I have replaced the air filter the engine has killed once at idle yesterday and today after it had sat for awhile I started it up, it revved high and kept fluctuating. I started to drive and about 10 secs after it kicked into Engine Failsafe Mode. I turned a few corners, shut it off for 5mins, took the air filter out and started it again. Ran fine back to my storage unit. Could the cheap filter be causing the problem? Need help asap as I would like to drive the car! Thank you!