EASY fix for my "death rattle" sound on 2011 Prius

I have had my '11 Prius for 5.5 years & over 150k miles and its odometer is a little over 200k. During a small portion of that time I drove it for delivery routes that forced the engine to run at low speeds a lot, which resulted in it running a little rough. (lots of driving at very low speeds & leaving the car in Park while delivering for a minute here and 30 seconds there)

Eventually the rough running progressed to massive shaking every time the engine ran at less than 3000 RPM (i'm just guessing the # by sound but i think i have a decent feel for the RPM range of the car). Autozone guy checked the reason for my check engine light and told me I had two codes for EGR system not working correctly.

Friend of mine who maintains his own Prius and used to be a professional auto mechanic, told me to try having the air intake and EGR cleaned out, which was going to cost me $700 at his buddy's shop (or he'd do it for $500 but i'd have to have it done when his schedule isn't busy). I was gonna bite the bullet and pay the $700 because being without any car at all is not a good option for me, but after reading on here that it's worth it to try spraying intake cleaner into the air intake, i did so. the shaking went away after running the engine hard for a few minutes during normal driving.

So here's my testimonial. It may be worth it to spend a few bucks on intake cleaner if your car is shaking. If that doesn't work, you can progress to more invasive methods like disassembling the intake manifold, cleaning out the EGR system, head gasket repair, etc. I may still have the intake manifold and EGR cleaned but i'll do it at a time that's more convenient to me, and maybe avoid spending big money renting a car at late notice and so on.