1990 f150 stumped. Need help
 

Hey everyone
I really need some direction here. I've done a tune up. Checked drive shaft. Brakes. And changed fluids. My truck will hesitate when putting in gear, in any direction. Reverse. Drive or park. Sometimes when I stop it almost feels like it goes into neutral, and it won't move unless I really give it some gas and rev the engine. It will also hesitate and shake at times when driving and changing gears. It almost feels like it only happens when I am coasting and press on the gas, like the engine is catching up to the speed? It is a automatic. The last symptom is that at times when slowing down I hear a rattle and it feels like the rear will shake and hesitate. Like it's having trouble downshifting. Ok. I think that's it. Thank you in advance for the help

What did your tuneup include? Did the problem exist before the tune up? Mileage?

Thanks hanky.
Let me give you some background since I am fairly new to auto repair. I bought it about 3 years ago for 700$. I did all body repairs myself. Changed alternator. Battery. All fluids and had transmission inspected. Wheels and tires. Cleaned the engine. Shocks. New power steering pump. Belt. I recently did a full ac repair to get it back working again. And the hesitation seems to be more noticeable since then. I cleaned all the spark plugs since they are not very old. But I have new plugs and wires on the way. The rattle and downshift shake has always been there. I believe it had 185,000 miles on it. Since it definitely doesn't just have 85,000 and it doesn't read over 100. I know I have a leak in the exhaust. But funds are a little low at the moment. I've done most repairs myself and am fairly competent, it's diagnosis where I get hung up. I'm just kind of out of places to start looking. And it's not giving codes.
Thanks. Dave