Carrier bearing?? Gas pedal moving over slow speed bumps. Vibrations through seat. Concerning clunk

So I've slowly been diagnosing and replacing all the little clunks clanks and vibrations that come with a truck with 270,000+ on the odometer (engine was swapped 140,000 ago runs like a champ)
Wheels and tires are brand new 31x10.5r15 Backcountry a/t at 33psi
So far I've replaced:
Shocks(5100s), struts, leafs (general spring with icon prog aal), body mounts, tie rods, ball joints, and I just did the sway bar links which actually helped my handling a lot. But there seems to be one component causing the majority of the poor ride quality I have been trying to diagnose since buying it. It definitely feels like something is loose under the truck... I get more than the usual amount of vibrations through the seat. hitting bumps at certain angles causes a hard clunk when the rear wheels make contact that shoots up through the seat causing me back pain. (Adding sandbags in the bed helped some but increases seat vibrations) As well as going over uneven roads especially ones that slightly rise and fall it feels like something is loose causing the truck to rock front to back (not side to side body sway is pretty okay after sway links). Seemed like it must have been a drive shaft issue so I assumed it was the carrier bearing and likely the u joints as well so I brought it to my local shop to have it diagnosed and fixed. They told me that the carrier bearing and u joints were fine but that whoever had previously replaced them had put the drive shaft back together incorrectly and that re clocking it would solve my problem. It seemed like it did help quite a bit initially but didn't fully resolve the issue and now about 4 days later I'm getting vibrations through the seat again as well as a new annoying/scary symptom which is in addition to the clunk I get sometimes when going over bumps at slow speeds from the front end now the gas pedal has started moving up and down when I hit small bumps, or with the rise and fall of the road, or releasing the clutch in low gears causing me to over accelerate slightly. Seems like it mostly does it in 1st and 2nd gear.

I inspected the carrier bearing and it looks to me as though it is old as I can visibly see cracks and wear on the rubber surrounding it. And can move the drive shaft around with my hand (I have a feeling that is normal but am unsure as I am very new to diy mechanics). Was my first instinct correct and the techs at the shop were just being lazy? I haven't done the motor mounts yet but have had techs tell me they seem fine but that is also a thought. Could it be something to do with the transmission? I'm pretty stumped and can't afford to keep having mechanics charge me for an unsuccessful diagnosis with the excuse of "it's a truck so it's going to ride like a truck" despite explaining to them that I have owned multiple other trucks and have many friends with first gen tacomas with similar suspension setups to mine so I know that there is something wrong. I would really appreciate any insight or suggestions this community has .

 

Inspect motor and transmission mounts with a prybar.