Engine speed suddenly drops-code P1580?

[bisync]

My '99 jetta (stick) drops to 5mph and the rpm shoots down at 20 mph or approx 2800 rpm. idles slightly rough (though not much) and at high rev in neutral the gas again cuts out at about 8000 rpm and catches back again once throttle is let up and down again. Can only really drive 15-20 mph before it jerks suddenly from sudden fuel stoppage and then the throttle needs to be let up again and depressed. if it is held down solid during this time i get no engine rev. Codes pulled read p1580 (vehicle speed or idle speed control, throttle actuator b1 malfunction) and p0103 MAF A circuit high input. could this be a throttle valve sticking or throttle body in need of clean or something like a MAF sensor problem needing a reset or being just plain shot? Or another possible malfunction, vacuum tubes?

[veedubmechanic]

did someone break the electrical connector for the MAF sensor when replacing the air filter so it doesnt click and stay on?

[Doc911T]

I am having the same problem with my 98. I replaced the rotor button, plugs, wires, cap, TPS, MAS and FPR and nothing has fixed it yet. As of last night it will not rev over 2000 RPM at this point I am lost. At full throtle is it blowing air back out the intake. I have had quite a few people tell me that it could be the CAT being cloged. If you figure out what your problem is please let me know.

Thanks
Shane
shane-yarnell@hotmail.com

[bisync]

Nothing has been broken in the way of electrical connections. Cat has some rattle which has been ongoing for two years, may be heat shield or weld or substrate inside, have to check on that. But connectors are fine. PCV hose is cracking, and has temporary fix. Cleared codes and still behaves same way. Thinking MAF.

[Doc911T]

On mine I just cut the cat out and it fixed my problem. Before I did so I replaced the MAS, TPS, FPR, Cap, Rotor, Plugs and fuel filter. It started doing what yours is about a month ago it got to the point that it would not go over 5mph. Unbolt your cat up front and see if it is that before you spend that much on a MAS

[veedubmechanic]

by 99 I am assuming you have a mk4 old body style due to the pcv hose cracked that you repaired. I would replace that hose, and remove/clean the maf sensor. Also if the cat is rattling that it needs replacement. If there is too much exhaust flow through the cat the maf will pick that up and read incorrectly.