Hard cold starts and trys to stall when taking it out of gear

Even with an optima style exide battery and synthetic oil my XJ still has hard cold starts. I have to give it some gas to get it going so I'm thinking it has to be the fuel pump or fuel filter. Also when I take it out of gear sometimes it wants to stall and the rpms dip down to below 500. This only used to happen when I was wheelin' and was going downhill and put in the clutch but now it's happening in town too. Anyone think that these are the same problem and if so is it the pump or filter or both maybe?

If you have not replaced the filter in a while, that would be first. Secondly I would give the tb a good cleaning, by pouring a can of seafoam through it. You might also want to replace the air cleaner and after the seafoam you should pull your plugs and replace if necessary.

What year XJ?

98, new spark plugs and a clean k&n

What about the engine temp sensors? MAT and CTS the gage temp don't count.

Also you say k&n air filter, hope you still use the air box and the intake air heater, thats need in cold climates.