XJjeepie

My 2000 XJ keeps having P0306 issues And I'm trying to figure out what is causing the problem ...I have replaced the crank position sensor the cam position sensor the coil pack spark plugs and TPS ..I drove it around yesterday and it ran great then I shut it down when out an hour later to drive it And it gave me a bunch of codes P0300,P0301,P0303,P0306 with a flashing CEL and rev limit So after I cleared those codes it ran great and then I got P0306 code again ..I will mention that under the hood Was pretty damn hot and the fuel rail and injectors were hot to the touch when I pulled back into the driveway ...any ideas as to what's going on?