Starting problem

Hello,
My 95 XJ (4.0 5sp) usually starts with about 1 second of cranking, even in the coldest weather. But sometimes, it will crank, but not fire. If I step on the gas and crank it, it will start coughing and eventually will start and run fine. What could be causing this?
Thanks,
Mikel

It needs a tuneup.

It has a fairly recent tune-up. It usually runs/starts great - This only happens esporadically.