I am having a very similar issue with mine. I did the same thing and the codes cleared. Then it came back with a P0301, P0305, and P0316. That is a misfire on cylinder 1 and 5 and a misfire on start up. Then all of a sudden I lost all power when I was on the highway. I had it floored and watched the RPMs just drop. I had to work the past three days and haven't had a chance to check it. I am thinking that either the catalytic converters are clogged or the sock filter on the fuel pump. I will keep you updated with my problem but you may want to check those possible causes.