Failed my inspection today with a cylinder 4 misfire code P0304 and another code P1494 which is Leak detection pump switch or mechanical fault.Can anyone tell me anything about the P1494 code? I was going to try replacing the cylinder 4 plug and see what happens but i'll take any info anybody has on either code.

IIRC, it can be something as simple as the gas cap not on tight enough.

When we pinged that code, it was because the evap hose plastic nipple connector had become broken off on top of the gas tank (2000 TJ).

Irreplaceable part, you need to replace the whole tank.