So I got this 1984 cutlass supreme right, & I went from a 350/700r to a 5.3ls/4l60e out of a 07silverado. I let a coworker’s brother in law do the work, come to find out he specializes in Honda’s/Acura’s 🤦🏾♂️ & my car was his first ls swap 🤦🏾♂️ 🤦🏾♂️.. good thing he didn’t charge me that much.. Anyway I get my car back a couple weeks ago and it won’t shift out of first gear. Also my shift linkage only allows me to select PRND, it won’t let me pull it down any further to shift manually. Driving it Gets up to about 25 mph and that’s it.... it doesn’t even have enough power to drive up on my trailer unless I’m goin downhill. It has more power in reverse, (strange I kno)He says it needs tuning then it’ll start shifting. I called a few shops and they all said tuning has nothing to do with it, it should still shift. it sounds like the transmission isn’t getting power. Anybody else had/heard of this problem??