what does codes P300,P301,p302,p306 mean and where do i start on problem on 2001 Toyota Avalon

changed spark plugs and running great until I stopped and got gas a little later it started misssing and cel started flashing. running so rough thought i was having a flat tire.

Asked by for the 2001 Toyota Avalon
poss coil paks are bad or circuit issue.have live data read to determine if its circuit or coil paks
1 more answer
Re-check all the coil/plug connections and IF it wasn't running like that before getting the fuel, take a fuel sample to be sure there's no contamination , although if it was bad gas , it should have all cyl. misfire..... AND follow #1 advice.