Wierd Issue, Is it my FFuel Filter
 

Start the car in the cold weather, but it's not a hard start or no start. Go to put my foot on the gas and the RPM's dip to maybe 500 before going to operating rpms. Has done this a few times now. Also noticed in my first mile of my drive tonight the RPM's dipped one time about 500 rpm's while car was warming up, no problems after the two I stated. I presume my fuel filter is the original(seeing as my brother only did like oil changes on the car). Car has a hair over 155K miles on it. Is my filter going bad? I have only now noticed this problem when it's cold outside also.

Sounds more like an air mixture issue... check air intake and vac lines, then possibly on to the throttle body. From there, temp sensors, etc...