Check the oil.
Failed lifters/rocker arms would not be uncommon.
No such thing as a 2003 Chrysler Pacifica. Your 2004 Chrysler Pacifica that was built in 2003 probably has a bad bearing in the blower motor. Unfortunately, the entire blower would need to be replaced.
That is possible.
Lifter noise is not uncommon.
Usually it's the lifters in the engine making that noise until they become fully pressurized with oil, then they stop ticking, like on the 3 liter caravans.
Bacause it was expensive to produce, and they were not selling well. The Pacifica was supposed to replace the town and country, but since that didn't happen, people kept buying the town and country. The dodge journey was produce to take over the Pacifica. With a much lower entry price point, it's selling better. Similar to the Pacifica, the journey took over the duties from the cancelled short wheel based Chrysler minivans.
Most likely it's your valves in need of adjustment.
Possible lifters that are bad that could explain your ticking noise. It should cost you nothing by stopping by an Auto repair shop and have them listen to your engine.
Its possible that this ticking sound is caused from driving fast for prolong periods. Its possible that its not the engine that is making the sound, but the exhaust system somewhere. I hear a ticking sound if I drive over 140KMh for long periods. It always stops once the car cools. I hopes this helps.
It is probably the lifters. I suggest using an engine flush and I have had luck with GUNK. Follow the directions on the can. You may have to do it every 30000 miles . I found that if I put a non Mitsubishi oil filter on my pu would start making that ticking sound
Faulty fuel pump
Have valves adjusted.
It is possible that a part of the EGR valve has fallen out. This will cause a very loud exhaust noise.