Hey Scotty I have a 2000 Toyota solara with around 104,000 miles and I have a check engine light for a p0420. Now when I go to start the car on a cold start she might stall but then catches her self and runs normal only one time did she stall completely and I had to restart her but when I did she started right up normally. I know you have a video for fixing code p0420 with lacquer thinner I have a 1 gallon can of it but I’m kinda scared to put it in my gas because I read it could damage other parts of the car but I trust you if you say it safe thank you and stay safe.
lacquer thinner *might* get rid of the P0420 code, but it won't fix your stalling.
Your problem is going to require some analysis of live data to see what's going on.
Thank you