2008 Expedition Limited with 130,000 miles

Expedition has been running completely fine. Saturday upon startup it idled very rough and would die if you did not give it gas to idle it up. As I went to go down the street it would buck and miss until the RPMs got above 1200 or so. Also if I gave it too much gas too quick, there was a loud rattle on the driver side. If I backed off the gas, the rattle would go away. Of course the CEL came on. I brought it back home and parked it. I finally had a chance today to take it to the parts store to get the codes pulled off of it. The parts store is roughly 15 minutes away. By the time I got there, the engine had smoothed out and was running just fine, no rattle, no missing. They pulled the codes and I had a P0018, P0022, and a P0171 (I believe that's what it was). I've read and read and read. I've come to the conclusion that it could be the VCT Solenoid. However, the engine smoothing out and running fine again has got me stumped. Any ideas on what it could be? I'd just as soon not go to the dealer if I can help it. Working on it myself is not an issue.