Engine skipping

[240sleeper]

Hi, I recently used engine bright to clean down my engine. Anyway, after doing so the car started misfiring and sounded like a lawn mower. After driving it for a day the engine regained normal idle and the car started running fine. Well now the weather is getting cold around 50 degrees and the problem has popped up again. The car sounds like this.. purrrBLIPpurrrrrrBLIPpurrrrBLIP etc. The idle often fluctuates between 500-750 rpms. It only happens when the car is cold and when im accelerating. I have checked all connections relating to the ignition wires. Any suggestions would be helpul. Btw does the ecu only spit out codes when the the light is on? I ask because I had a ford with many problem codes but the light never came on. Thanks

[C-Kwik]

Sounds like one of the cylinders may be missing. Check to make sure your ignition wires are in good condition. Check your plugs. Also check the connections on your fuel injectors.