Hey everyone, I have a 2001 Discovery. I love it and up until now have had no problems. The valve cover on the passenger side was leaking, so I figured I should go ahead and do a tune up while I replaced that seal. I replaced the valve cover gasket, changed the plugs, and the plug wires. Yes, I did have to take the intake off to change the gasket. Everything went well during the change. When I went to start it, it purred like a kitten. At least until it hits 1500 rpms. Then I get a blinking check engine light. I get a cylinder 1 misfire and a multiple cylinder misfire codes. Now I have went back to check the wires and plugs, all is good. What could be my problem?

 

By the way the vehicle has 79000 miles and the codes are P0300 and P0301.

 

No help?