I have a 2003 V6 mustang
convertible. After my car is warmed up and the radiator fan turns on the rpm's drop to under 500 and the car shakes as if it will die then it jumps back up then settles back around 750. When the fan comes on again the process starts over.
I have a new alternator (motorcraft), new wires, new plugs, new air and fuel filter, new IAC, new TPS, new EGR and have seafomed and change oil regularly.
When I bouth the car (almost a year ago) it had a dead batter and the guy replaced it with a no name battery... it literally says battery on the sticker... could this be it? I dont think so because it starts fine everytime
Also the ac cause the issue (because the fan is turning on) and using the power windows drops the rpm's also
What can I do to try to fix this? Any Ideas or suggestions is greatly appreciated!