So yesterday I had some time and replaced the idle air with one I had on the self of questionable condition. It died automatically. I cleaned the old one and re installed it. it ran about the same. I ran the engine without the intake manifold hose on and surprisingly ran ok. weird. so this got me thinking about the mass air. I don't know how or when it plays into regulating the air fuel mixture but I unplugged it while the engine was running and it had a direct impact on a sudden increase in how the engine was running. (keep in mind that there is no air passing though it). I reinstalled the intake manifold hose and plugged the mass air flow sensor in and fired it back up. Back to running rough. I pulled the connector for the mass air and it cleared up. It was clearing running rich but running far smoother then normal. I hope to replace the mass air flow sensor with a spare I have on the shelf and see what happens. It is the original unit so its 25 years old. Do these units go bad, what is the failure mode and can I repair it. It looks pretty simple? Any input would be greatly appreciated. Its kind of suspicious now because the reason I hadn't been driving it for a while was because it was getting terrible gas millage compared to what I remembered. But after not driving it for a few months I didn't know if I just forgot how bad it was or if I was just loosing my marbles. <img src="/forums/images/graemlins/confused.gif" alt="" />