I changed my oil in 1989 xj6 jaguar same way i always have .I went to start it up and all it would do is crank so i replace fuel filter, fuel pump,plugs and rotor ,dis.cap plus fuel regulator ,replaced battery .Still it only starts and run only if you clean throttle well or spray starter fluid in mas intake will run good with a little high idle when stopped now but when you turn off will not start again.Can someone please answer this crazy jaguar riddle for me cause other than replacing stepper motor or poteintmeter (throttle position switch ) i am at my wits end . thank you

Yes continues to run fine just a little high idle when sitting .when i turn car to off it will not start back up . Unless i spray more starter fluid in mas or clean intake out really good