My '04 Aveo is an automatic that I've been driving for about a year now. It has been pretty stable until last week when it over heated and blew a head gasket. I replaced the gasket and put it back together. I cranked up, it sounded like it was running OK for about a second before the engine RPM ramped up to 4 or 5K rpm before I could shut it off. I checked at the throttle pedal, the cable, the throttle body (closed), and tried it again. About half second after ignition, the RPM accelerated to its max and there is no movement at the throttle body and the throttle plate is in the closed position. I swapped out the IAC and TPS and the same thing happened. Performed a visual inspection to inspect wires and plug connectors for frayed or obvious problems. The intake manifold was never removed from the Head during the gasket replace so I'm ruling out intake to head gasket leaks. I looked for OBDII codes and nothing. I won't keep it running long enough to get any live data on my meter for fear something will break. I disconnected the battery for 10 seconds to reset the computer and started it again with the same result.

I'm at a loss. I've never seen this before. Does anyone have experience or suggestions ?

 

Just a follow up on what appears to be a possible solution or at least it is working for the past few days. I disconnected the battery for 3 minutes and unplugged the MAF sensor. After reconnecting the battery, I attempted to start the engine. It cranked and started with an idle around 900-1000. I can live with this. I shut it down and plugged in the MAF sensor and started it and again it idles around 900-1000 rpm. I cleared the OBDII codes as they all related to the MAF sensor. I've taken it out for a few test drives and it seems to be working well with no OBD codes. I think I'm done. If anything changes, I'll give another update.