instant trans shudder

hello experts.First off I am sorry for the length of this post. I am stumped here and have been careful and trying to keep this car top notch.
I have a 92 lesabre. Have replaced many parts as maintenance.Car had small tranny shudder on thrusday.hmm plugs andWires!! Tranny fluid was done in december.Car was running great until I changed plugs and wires,Idles slight up and down now and harder to start. Now I must place foot on gas when I start it. Changed fuel filter pvc with all grounds clean. Cleaned map, iac ,throttle body ;vac module works but havent cleaned egr yet.All AC delco. Some where along the line Ive developed a bad tranny shudder. If car is at 1k rpm over drive and i come upon a hill and i even baby throttle it shudders through . If its a big hill its like its going to stall and the bang bang clunk from underneath.From 2k- 2.5kthe revs will drop 500 it will thunk, bang or backfire a sound until I letoff then bounce back up to 2k.. 1st to 2nd is brisk and smooth , 2nd to 3rd and 3rd to 4th is I feel the pull level off at 2k rpm and if I push it to hard from there without easing it through Ill get this horrendous cut out and noise.When the car indicates its about to cut out/shudder, if I touch the brake the revs will rise normally and then retreat to the proper rpm where I must baby it along. Passing speed performance kick down it just convulses.must coax it to higher rpms.I can make the car do this in all gear selections. So my thinking is this is ignition or engine related and not trans mission. ( I hope) Funny the other night i was driving home from hockey in the pouring rain and the car sounded like the exhaust was agaist the floor boards or pipe was separated. I was a couple miles from home and it stopped makin g the noise and it was back quiet as usual. Jeepers I dont want to mess up my tranny. could ICM be bad. ( cleaned base plate on it too)I checked coils and the spark is blue.thats as far as i got .Ex haust seems clear .I put my hand on it and its got lots of push. I did notice a small dent in the tailpipe.elbow.Cats three months old. Imjust throwing these things out there guys.
Also a secondary issue,( hope im not breakin forum rules) I had a new harmonic balancer put on the car and it still knocks. Ive removed the belt and checked the AC and other belt acsessories and i cnat find the knock till i put the belt back on. Stethoscope finds the noise muffled in the rear motor mount(passenger side)( all are tight and none broken) and the other corner of the motor its loudest through the ac compressor. I cant feel knock on the balancer its self. Could the balancer be faulty. Its a new dorman and it does have a small wobble in it. I measure about 2mil wobble. Mechanic said they all do that and these motors knock abit. It knocks pretty loud when its warm from a stop.. I can turn the crank balancer by hand a full turn but im strong and I think Im turning the motor. Or am I turning the metal ring by hand cant see that well, no room. could the knock be the main bearing and the belt pressure is just pulling up on the crank through the balancer. Balancer bolt doesnt appear loose . Could the balancer be off center. Cheap after market??
My Car ran great till Saturday.What did i do??? ive researched and read so much. Not sure what the answere is.need fresh ideas Im trouble shoooted out.
thanks steve

I hate to say this, but you need to go back and check everything you did. Check all the plugs to be sure none were cracked or broken, then be sure the wires are pushed tight enough on the plug & coil terminals to here/feel a click. Have you checked firing order? Did you notice two O-rings on the PCV valve and did you replace both? Contrary to what the mechanic said; the balancer should not wobble and all these engines do not "knock a bit". The belt would not silence a rod or main bearing knock, so that is not the problem. When you had the belt off, did you check for play (side-to-side) motion in the water pump, power steering pump, & alternator pulley? How about the idler & tensioner pulleys? If all that checks OK, remove the balancer and check for a cracked hub. Be sure to inspect the crank position sensor and reluctor rings on back of the balancer for possible contact. You have a lot of work to do!

I hate to say this, but you need to go back and check everything you did. Check all the plugs to be sure none were cracked or broken, then be sure the wires are pushed tight enough on the plug & coil terminals to here/feel a click. Have you checked firing order? Did you notice two O-rings on the PCV valve and did you replace both? Contrary to what the mechanic said; the balancer should not wobble and all these engines do not "knock a bit". The belt would not silence a rod or main bearing knock, so that is not the problem. When you had the belt off, did you check for play (side-to-side) motion in the water pump, power steering pump, & alternator pulley? How about the idler & tensioner pulleys? If all that checks OK, remove the balancer and check for a cracked hub. Be sure to inspect the crank position sensor and reluctor rings on back of the balancer for possible contact. You have a lot of work to do!
Okay back to check everything.Good advice.check the grounds wires everything. Thought i had that covered. Pinched wire ?Ill check > Im thinking something was on its way out and since i put the new plugs and wires ignition be cause of the slight shudder. or fuel regulator perhaps.But it was runnng so good till the wires and yes theyre on the right cylinders and towers. My knock could be a miss fire because I feel no knock on the actual balancer transfering thru or arouind that area or a knock through the engine pan either. Ill get this shudder issue sortted then the balancer ,or the balancer may be part of the problem from the wobble. I believe Im going to have to break down and take it to the dealer and have it read. Electronics are beyond me. Dont have a scanner.By the way ,The site here has been very valueable to me too. thanks so much . And now Try and find a new mechanic who will share information and not try to tell me something isnt there when it is.

Went back checked evrything with the meter. Car ran even worse on the way home after a ride with tech. He thought igniton. Im thinking coils darn it. Next day found out it was a defective spark plug. I had the new plugs and wires off twice and checked them for resistance and flow and the same with the plugs and the plugs looked fine. I suppose once I had aload on the engine then this plug acted up. Freaky. I was freakin too.I was very careful putting the plugs in so either I did something to the plug or it was manu defect.( my comedy continues) I also had the tech check the knock too with the new balancer. He thought main bearing. this car has only has 225k km on it. and its always been serviced properly. but thats another thread of discussion.
Thanlks
steve