2013 Prius Wobbles at certain POWER settings

Hello all!

I recently just put a new head gasket on my Prius. I replaced the EGR cooler and valve and PCV with all new components. Also cleaned every component that came off while doing it. The vehicle has 260,000 miles on it. It is worth mentioning that I have had all four tires replaced recently with a balance and a recheck of the balance. The symptom of the wobble feels very similar to a tire imbalance, except it doesn’t have anything to do with the vehicle speed, but only specific power settings.

I have been driving it for 500 miles now but ever since I have changed the gasket I have had a “wobble” at speeds approximately from 30 miles an hour onward ( ONLY when the engine is on ie. not while in EV mode) at approximately 1/4 throttle demand and a little over half throttle demand Regardless, if the vehicle is accelerating or decelerating ( at those power settings). It does happen at all speeds like I mentioned.

There is no rattling associated with the wobble. The engine starts and runs great!

I have my suspicions on what it is, but I want to hear what other opinions are.

thanks in advance!
AJ

 

I changed the front tires with a pair from my parents Prius with no improvement

 

Did that with same symptoms

 

UPDATE:

in an effort to diagnose what this wobble is, I started with the low hanging fruit. Since I changed the EGR cooler and EGR valve to brand new units, I decided to eliminate those out of the equation by unplugging it. Lo AND BEHOLD, IT WORKED! Of course, the car instantly gave me a check engine light.
Now there is no wobble from any power setting. Again, there was no knocking or pinging or any type of poor engine running indication, other than it felt like the tires were unbalanced.

I will contact the Toyota that I got these new parts from and talk to them about it.