JGC2000

Hi everyone, my 99 4.0 GC at cold start makes a squeaking noise accompanied by a knocking noise that goes away at anywhere from 30-90 seconds depending on the outside temperature. It is not a valvetrain noise, I can actually "feel" the noise when I put my hand on the drivers side fender. It sounds like someone knocking on a door lightly (in perfect time with the squeak). Again, it goes away pretty quick and does not return unless it sits overnight or after a day at work. I could drive it all day and it won't do it again all day, only at a completely cold start. The motor has just under 159K, and has some slight piston slap at start up too (related?) The squeak sounds like a pulley, and seems to emanate from the drivers side front as well. Any ideas? I experience no ill effects while driving and the engine is very strong all the time. I find it interesting that its duration is based on outside temp.

Thanks!!!