Engine hesitating with moderate throttle

[MVarelas]

When driving with moderate throttle sometimes the engine hesitates in half second intervals. It is a subtle hesitation that feels like little bumps in the road. It happens most often while using cruise control in 6th gear when going down a hill at low rpm (1600-1900rpm, 55-65mph). The truck has 90,000 miles and has been doing this for about 5,000 miles. I have also noticed that sometimes when idling, the engines hesitates for a split second which is very subtle and is probably only noticeable to me because I am very accustomed to how the engine usually idles.



One other thing which I know is likely unrelated: The engines is now running a few degrees hotter than it used to. The gauge seems to sit in the middle at 200 degrees while it used to sit slightly to the left of middle which I would estimate was around 195 degrees.



The truck is a 2004. 5 4wd, 6th speed manual which has only seen very light use, mostly long highway trips at 62mph with no load. The truck has always been properly maintained and still has the hesitation problem with a new fuel filter.



What do you think the problem is and what do you advise I do?



Also, do dealers get out of warranty work if after market fuel filters were used instead of the overpriced Mopar filters?



Thanks very much, Mark Varelas

San Antonio, TX