I did some basic engine maintenance and after I finished I started the engine and it made this horrible rattling noise. The engine struggled to stay running, almost died then recovered and smoothed out. I drove it around the block and it was smooth as silk and ran better than ever. My assumption is that I sprayed too much throttle body cleaner down the intake tract and despite sitting for an hour before startup the puddle of fluid must have caused the engine to choke. Any ideas? Ohh I almost forgot, my MAF was extremely dirty! There appeared to be a chunk of soot covering the 2 wires such that I couldn't even tell there were wires in there. The PCV was dirty but operating just fine despite 128k miles.