If the transmission delays initial gear engagement after being parked overnight or longer, it may be due to a suspect transmission cooler return filter. If the transmission was recently serviced and the part number for the cooler return filter contains an "AB" suffix at the end, a new filter should be installed.Google+
Car Problem Reports
Dodge Ram 2500 Replace Transmission Cooler Return Filter if it Has "AB" Suffix At End
Dodge Ram 2500 Problem
Drive Train Affected: 2WD
Visitor, 1996 Dodge Ram 2500, 2WD
After sitting for 24 months transmission delays shifting 2nd to 3rd.
Visitor, 2005 Dodge Ram 2500, 2WD, 110,000 mi
My truck does exactly this. I put it in gear after it has been parked overnight and it takes a few seconds to engage in gear. I recently had my transmission replaced.