low voltage

I have a 2009 Dodge Grand Caravan 3.3 L with 268806 miles C/V trim, but having random limp mode issues for 5 years. No one can figure out the cause. Thunderbay Dodge could not find the issue, and Criswell Chrysler Dodge as well. Factors that seem to cause the limp mode: Ambient air above 70...

1997 Ram 1500, 5.9L Brand new alternator and battery. An alternator test done by Autozone sees 12v going into the battery, not the 13.5v they're expecting. We think there's a drain somewhere. Possibly related issue: recently the "maint required" light came on. Checked and there's no error...