You have one of three problems happening. Low fuel pressure, plugged cats or a bad MAF.
Have the fuel pressure checked and get an exhaust backpressure test done. The MAF is going to need a scan tool and someone who knows what they are looking for to diagnose it. Have you tried cleaning it?
Long time ago I replaced the OEM exhaust stuff with the Random Technology YPipe and Cat with Magna-Flow exhaust. Eventually found a bad O2 Sensor in the CAT. Couldn't get the sensor out of the CAT, so I just ordered a new Random Technology CAT and got a new O2 sensor. Haven't had a problem since.
I didn't know the fix, either did FORD or the Friend Shop. So basically just threw money and parts at it until it was fixed. Probably invested like $1500. But oh well.
The tapping is constent. Better at higher RPM. When I drove home today I turned on the AC after I got up to speed. The cold air did not blow till I slowed down to make a right turn at low rpm.
Not sure what this means. Kind of meaningless. Is it relevant?? How long was it between the time you that you turned-on the AC and you made that right turn? How hot was it out?
I ran for about 3 min and turned the air on. After about another 5 to 8 min at 40 mph I had to slow way down to turn right. When my rpms dropped, my cold air started blowing. It was 90? today.
