1994 Jaguar XJ6 starting problem

My 1994 Jaguar XJ6 will not start in the mornings or after sitting for a few hours. If I drive it and stop for a short time it will start right up. But after a few hours of not running it is so hard to start. It cranks fine and could take 5-9 tries before it starts. But if I drive it and stop for a short while it will start again fine on the 1st try. I had the fuel pump and fuel pressure regulater replaced and this didn't solve the problem. It also had a full tune up dun, wires plugs cap and toter. Still hard to start. One other thing is happening, when the car does start it makes a bad niose almost like a belt but its not a belt. I was told it was a air pump? Could that have anything to do with the hard starting problem? The dealer doesn't know what else to do, can you help?