318 running rough and losing vacuum when in gear.

I'm sure this has been discussed many times but here's my issue. 1971 dodge dart 318 2bbl cast intake. electronic ignition. 727 auto. only mod. is the elec ign. was running fine with it.
first started when cruising home and I would be running at a certain RPM. car would start to run like it was running out of gas or missing. if I gave it a little gas or let off on the gas it worked fine. came to a stop sign and the rpm died right off and car was shaking and hunting. noticed my power brakes were not working. idles not bad but if you gently apply the throttle it has a spot at low rpm where it bogs, runs rough and no power. give it a little more throttle and it picks right up. at idle if you apply brakes or put in gear the car almost shakes apart and runs super rough and rich. thought power booster leak? nope ! here is everything I have done since to try and fix it. booster plugged still does it in gear.
plugged power brake vacuum port.
did complete vacuum leak check several times with spray can, propane you name it. no leaks
new dissy, cap, rotor, wires, plugs. to verify (bought second set of wires, cap,rotor, plugs)
new coil and ballast
complete carb rebuild
new egr and cleaned port. no luck. plugged egr port.
new PCV and tried plugging
set timing several times. has to be very advanced to idle fairly smooth.
got feed up. installed new aluminum intake and 4bbl. looked at cam lobes, lifters and rockers.
new fuel lines and filter, gas tank vent. even remove gas gap to ensure vented. fuel pump has good pressure.
nothing helped at all.
I am positive no vacuum leaks, timing is correct, firing order is correct, operating temp. is good. oil level is good. had someone else verify timing and firing order and check for vacuum leaks encase I missed something.
I have a tranny leak but I keep the fluid up. Only other thing is besides leak is when I put car on stand I cannot turn the back wheels by hand unless I have it in neutral. but it was like that before the engine started acting up. tranny seems to be shifting fine.
I know it was long. just trying to avoid having a long thread of questions that I should have included myself. thanks
Keep er STR8UP and between the ditches!!!!!!