I know zero about vehicles so not even sure it's the
Tranny but when I go from like 30-40mph excelerating
There is a slight delay and light vibration. Any mechanics know if this is
Something I need to bring in asap? Don't want to put it off if it will damage anything.
It's a 2013 4.0 that I racked up 167,000 miles on. Could it maybe be a timing
Chain or belt?

I would think more possibly a driveline problem. Carrier bearing or pinion bearing. Or maybe even needle bearing from transfer case. Go on Tacomaworld and post. I’ll guarantee someone will have an answer for you in a short amount of time.

I had some similar vibration issues on my 2016. Would happen in about the same speed range as you describe. More so on deceleration than accelerating. I could feel it in the steering wheel, so figured it was a wheel bearing.
Turned out to be the needle bearing in front of transfer case. Was out of warranty and Toyota covered it 100%. Plus a free tank of gas for my troubles.

I had a 2013 the same as yours. I had a vibration at about 20 mph. I had it in a few times, complaining about the vibration. They could not figure out what it was. It never gave me any problems, it was just a vibration. I now have a 2017 Tacoma. This transmission clunks when it down shifts into either first or second gear. Also when it down shifts into first gear it will sometimes speed up—make a little jump forward. The dealer did not know what the problem was. A few days after I had it in, for the second time, the dealer called and they had called Toyota. Toyota told them to reset the computer and let the computer relearn my driving habits. That fixed the problem. Now, about 9-10 months later it is starting to do it again. Not very often , but it's doing it.

Maybe if you can have them reset the computer, the computer can relearn the transmission shifting patterns, and eliminate the vibration.

Certain years had a Driveline recall. Not sure if 2013 is included. I think 2006-10 for sure. The driveshaft and universals would come apart. So check that.
Also Check the Carrier bearing where the two shafts meet.
The delay Part could be transmission slipping also and shuttering is the vibration felt??
Lift kit on the truck?? could need a carrier bearing drop kit. If it only vibrates at 30-40mph or so. Mine does with a 3 inch lift.

The 4.0 is the 1GRFE motor its timing chain and so far proven bullet proof.

Thanks for the info guys. If it seems to get worse or doesn't stop I'll take it in, only Toyota dealer
Is an hour away but I get down there fairly often.

besides Tacomaworld site you'd be wise to ask at www.yotatech.com too

ALL yota owners should belong