SOLVED! After a couple hundred miles and a dozen drive cycles, still no codes. No stumbling. It was a vacuum leak on the gas tank end of business.

Confirm fix please. Still good?

Once you're at speed, the engine is in a sort of steady-state that is mostly governed by the ignition system utilizing the fuel being delivered by the main fuel line. During changes in in engine load such as starting from a stop, the "EVAP" system turns on and delivers fuel vapors to the i...

There are geared cables that transfer power from the motor to the rail?. They can become detached from their connection..

Nexmex> Smoke test your gas tank. The vent valve hose and filler neck hose has a tendency to crack.

Vacuum lines and undercarriage fuel lines may be badly rusted/degraded. Leaking oil through oil cap (easy fix but if left untended for a long time may have fouled up engine compartment with burned oil). Wiring harness under the engine cover may be burned. A/C compressor shot. Brake booster leaking (...

Photo of the leaking hose attached:

So here is the latest update: I went to the Midas again because they have done so much for my car (brakes/struts/some sensors to chase the above problem) that they do a lot for me for free. I told them to smoke test the gas tank (which no one had done before - amazing) on suspicion that my intermitt...

I told them to do the ignition wires too but the part is not in stock. I really want to replace all the ignition components because I know how high voltages can fry parts. EDIT: Now I understand what they mean by the part is not in stock. Because it is a coil-on-plug setup, the only wires running to...

The codes are P0455 and P0172. The car hesitates from a stop (either no sound or a slight choking noise) but recovers after releasing gas pedal or pressing hard on gas pedal. There is also a bit of surging below 30 mph after the hesitation. Sometimes idles rough after driving a long time and then tu...