Rough idle no CEL
I have a 00 Mustang and the idle is rough between 1000 and 1500 rpm and shakes when I start going from 0-40 mph then kinda smooths back out. But it still drives poor. It also shakes as I'm coming to s stop when the rpms drop in the 2000-1000 range too. I took it to a friend who is a mechanic and him and a few other guys can't find the problem and there is no CEL on and the codes read fine on the car. They tell me its a ghost problem and they are stumped to what it is. I replaced the plugs and wires and cleaned my TB, IAC, and CIA Filter. I was going to replace the fuel filter next but I thought I'd ask on here for some helpful advice on what to do next??