Low idle vibration weird exhaust sound

Hello I'm new and having a problem with my 2007 tacoma prerunner 4.0l 187,000. For several months now idles at 500rpm, exhaust sound different and some sort of vibration. I think mentioning driving conditions just in case it helps. I camp in thr summer months and put the truck through a lot. Meaning I don't use thr brakes, I use engine brake a ton towing about a 1600lb popup. Typical rpms down hill no gas is 2400 rpm. Somehow I think this may have caused the issue. Changed pvc old one was a little stick but still worked, briefly cleaned throttle body outside only. Cleaned maf. Weird thing is get a clunk when at a stop and ac tuns off. Like the truck got rear-ended. Any help would be great.