Rough idle, stalling, falling gas mileage
 

My car started to stall occasionally when I would come to a stop of make a slow turn, but only before the car reached normal operating temperature. It has progressed to stalling during operating temps and the idle started to surge at all times. I decided to change the PCV, O2, TPS, MAF, and IAC sensors. I have also changed the fuel filter, plugs & wires, and all three ignition coils and cleaned the trottle body. The problem still is still there and is getting worse. My gas mileage has suffered greatly. I was avg 27mpg and now I avg about 14mpg. The idle is so bad now that the car will barely run in park with out giving it gas.
Other than the high consumption of fuel the car rides fine during driving. I did notice that idle is better if I disconnect the vaccum hose to either the FPR or the vapor canister. I have read many posts on similar problems, but I never found a real solution. Any ideas is appreciated.

Two things come to mind. Fuel Pressure Regulator and Fuel Pump.

You'll need a fuel pressure gauge to determine which is the problem Pressure is probably low due to worn out fuel pump.

I'm leaning toward the FPR also, because the fuel pump is less than a year old.

You should still use that fuel pressure guage to check before you throw more money at it, IMO.

I agree, test it with the vacuum hose hooked up and then remove it. When the hose is removed it defaults the system to max pressure.

Is there no codes ?

The CEL does come on, but goes away when driving. I'm going to have it scanned on monday. Thanks