2006 Chrysler Pacifica

Engine Performance problem
2006 Chrysler Pacifica 6 cyl All Wheel Drive Automatic 60,000 miles

I own a 2006 touring AWD with 59,800 miles.

Over the past few thousand miles, I have noticed what can best be described as surging when accelerating. I notice it most on a warmer day while using the A/C. I also noticed it the other morning while driving approx 76 MPH, (our highway speed limits are 75) pulling a steep hill. The tranny shifted down to 3rd, I was not running the A/C and it was approx. 60 degrees F out.
The pac hasn't thrown any check engine lights and it is idling fine. The condition isn't getting any worse although; the power and fuel mileage are down a bit.

I replaced the plugs with factory platinum plugs @ 30,000 miles. I recently replaced the pcv valve. I also checked the condition and gap of all of the plugs. They were all the same light tan color. The gap was perfect. I used an ohmeter to check the resistance across the coils however; I was told that the only way to detect a bad coil is while it is under a load.

I have not checked the condition of the fuel tank sock or the fuel pressure.

UPDATE: The symptoms now exist under all driving conditions regardless of vehicle speed or load. Still no check engine light.

Does anyone have any suggestions?
September 29, 2010.

Check fuel pressure 58psi if good run some SeaFoam in tank to clean fuel system

Sep 29, 2010.
Thanks for the suggestion.

I'll check the pressure right away.

Sep 29, 2010.