My daughter has a 99 Intirgue, 3.5L. It has recently been difficult to start the car after it has warmed up (i.e. - if she drives it, turns it off and then tries to go somewhere wtihin 20 mintues it's difficult to start the car). It also will start to idle rough when you are idlying in a stationary position for a few minutes (sitting at a long light at an intersection)..... almost feels like it wants to stall. Seems to be ok when you engage in drive and start moving. I'm not sure if its' related but 6 months ago the car sounded (and felt), like it started to idle louder and the car "rumbles" when you accelerate.

The Serivce Engine Soon light came on, but I replaced the CAM Sensor and that fixed the warning light. It's now back on again .......

Ive also replaced the fuel filter with no change in the problem..

Any thoughts?

Thanks, Rick

It cvould be a number of tthings, but since you replaced the cam sensor you might want to check the crank sensor as well. Usually the crank sensor will trigger the cam sensor and both need to be replaced.
Go to autozone or somewhere and get the codes from the check engine light and that will tell you for sure.