Need help I have a transmission problem

[6.0L_stroker]

I know this is the wrong site to be asking this, i have a friend that has always been on the dark side of american brands. Not to name anything brand but he drives a truck that says hemi on it, its a 2005 slt crew cab. The problem with the truck besides it not being a is that when you come to a stop and "try" to take off it seems like the trans isn't engaging and he said you have to put into first to fix it, what i was thinking is the trans filter might be cloged up it has 78K on it and hasnt had maintance done to the transmission. Does that sound right, because the sound of what he was saying is that it seems to be stuck in overdrive, so after a fluid and filter change what would the next thing to look at be, he is going to the dealer to get his pcm reflashed due to a mds problem as well, so does it sound like a torque convertor problem or a solenoid problem if that doesnt fix it