I recently tried to get my car IM certified here in Anchorage, AK. The shop told me that it wouldn't pass because my Check Engine light is on. It's been on since I bought the car in Texas, where, apparently, the IM laws aren't quite as strict (yeah, I know I should have dealt with it there, but...it's a long story). The shop plugged into my car to see what was causing the light to be on, and the error that it came up with (I don't remember the specific code) pointed to the tumbler valve. I was then told that it's a $1,200 part, and that I had to get that light to go off to get it to pass.

I took it to a Subaru dealership (I was buying nuts for my hood scoop) and brought up the problem to the guy who worked there. He said that folks bore that part of the intake out for increased air flow, so chances are that I don't even have tumbler valves, as there was evidence of modification (an up pipe) on the car that I had not done. He suggested that I un-hook my battery and let the car sit for a while to reset the sensors.

I un-hooked my battery to try and reset the sensors, then took it in again (to a different shop this time). The shop told me that the sensors hadn't had time to sense properly (please forgive my ignorance of the jargon), and that I needed to drive the car around for a couple of days and bring it back. It's a couple of days later, and my Check Engine light is back on, like the old friend who I want to leave my house, but just keeps on drinking my beer, smoking my cigarettes and hitting on my girlfriend.
The light came on after approximately 50 miles of driving.

Is there anything that I can do that doesn't cost $1,200? I have way better things to do with that money than something as un-romantic sounding as a tumbler valve...

Thanks in advance!