Car lost power, now idles low/won't stay running, Need help ASAP Options

[Mockmaw]

Well, my car is currently stuck in Kettleman City, broke down on my brother in the process of bringing it back to the Bay Area.

So.. after driving for several hours, the car began losing power (rpm still up there, just little to no power output.) He made it to the gas station right as the car died. Now the car will start with a little effort (that is, pressing the gas pedal), but idles very low before dying. Brother claims that there was a strange, repetitive noise when the engine was losing power.. similar to a pinging noise.

I'm about to embark on the 220 mile trip down there to see if I can figure something out. I'm beyond agitated as I just took the car to the shop to take care of a few oil leaks. Aside from the leaks, the engine ran beautifully.. since getting it back from the shop, it's been a real pain in the ass. Took it back to them, apparently they took care of the problem.. I guess they didn't. So what could have become f**ked in the last couple weeks? It's not fair for me to pin the blame on the shop, but I can't feel but cheated that the car ran perfectly before I sent it in.

So what can I do? What should I be looking for? I realize this is a hasty post and probably lacks some crucial details, so please ask for clarification where needed and I'll do my best.