Help with Daily Driver? Please?

Hello Y'all! Hopefully Everyone and Everything is Great far All Y'all! Ok Here's what's going on. I have an 07 Dakota with the 3.7 recently every now and then it seems like someone's tapping the brakes. Right now it's kind of the only daily driver I have and the gals been using it to go to work it's almost a hundred miles a day around trip. It's been stalling a little bit but also it seems like the transmission is locking up or something. I checked the fluid yesterday, before she went to go to nightshift. it was 2 quarts low, so I put two quarts of ATF plus 4 in it, checked it it was good, But the other side of dipstick it looked like there was some funky dunk on it. In other words look like black particles kind of crunchy looking I should have took them and put them in the sunlight a little bit better with some eyeglasses on or took a magnet to them. So she went to take her drive to work and she came back a little while later and said that it was running three grand at 70 normally it's running quite less than that. Also though right about the same time the check engine light started flashing on and off sometimes, intermittently in other words. I don't even know what to do right now. She can't take my duster right now the Harley's not finished and her amigo doesn't have headlights and they will not move her to day shift. She's in a management position for a national food chain, so this could probably be pretty grizzly. Is there any direction any y'all can point me into to make any quick checks? Is it possible something electronic got jammed up a little bit? Again I want to restate this sometimes when you're driving the truck it seems like someone's jamming the brakes on for just a second second. It seems like that only happens in fourth but when it stalls it's in first. I don't know what to do, I don't have a manual for the book I was hoping some of the pros on here to deal with these things on a regular could throw me a few pointers on which way to try to pull some quick diagnostics so I can do a process of elimination spreadsheet.
Anyway Love to all Yall and your Family's Loved Ones! I hope everyone is Well!
Thank You!