HELP! Engine Surging and Dying at Idle.
2000 Focus SE 2.0 DOHC ZETEC w/Auto Trans is wanting to idle at correct RPMs, but then drops down and goes right back to correct idle and does this a few more times and dies. Eventually, it gets worse and is hard to start without applying gas peddle when turning over. Yes, I know it's not carbureted, but its the only thing that works, even after leaving the key in the on position for several moments. I do hear the fuel pump prime when the key is in the on position. BTW no CEL, I did have codes for misfire, IAC, and TPS, but those I have been cleared
Here is what I has been done so far:
Fuel filter - filthy; ignition coil - cracked and out of resistance spec; spark plugs(Motorcraft) and wires - done right before I bought it; IAC Valve (MC) - nonfunctional; TPS - had TPS for manual trans on it; PCV hose (MC) from intake manifold to steel tube - collapsed; gutted cat - wasn't clogged but what the heck; cleaned MAF w/MAF sensor cleaner and throttle body w/throttle body cleaner; and finally cleaned contacts and ground points for fuel pump driver module; 2 bottles/fuel tanks worth of Chevron Concentrate Plus.
Car seems to drive fine, but can't idle and dies at stoplights unless I keep one foot on the brake and the other foot steady on the gas peddle in order to keep idle up. I have extensively checked all other vacuum lines and intake connection points (i.e throttle body, IAC) 3 times over with a propane tank to find leaks and there are none. Nor have I been able to locate any other collapsed or brittle hoses or elbows. I'm at a complete loss without suggesting the fuel pump, but it drives fine with hesitation so IDK. Any help is greatly needed; it's my daily driver for school and work.