Scotty,

I have a 2009 Pontiac G3 automatic. I have had several issues with this vehicle but it’s paid for and gets me from point A to point B. It sporadically has a hold light that comes on at highway speeds and prevents me from shifting causing it to stay at 4K-5k RPMs until I pull over or exit the freeway and come to a complete stop for the light to go out. I can then drive with no problems. 
it also had power issues a while back and several mechanics couldn’t figure out what was wrong. Took it to a Chevy dealership and they diagnosed it as needing the cat replaced. Because it has two of them they wanted to replace the one connected to the exhaust manifold which the part alone is over $800. So I hollowed out the cats because missouri is not an emissions state. It runs fine now, but my gas mileage has plummeted to around 21 mpg. Factory states 34mpg highway. Is there any way to get better mpg?  My Check engine light keeps coming on because of this also, but is it worth constantly clearing the codes (P0131 and P0420)? Does the computer adjust my fuel ratio based off the codes being there or not? 

I also get engine power struggles after I’ve just left my house down a county highway into town and am driving at 35-40mph and feathering the gas pedal. The engine starts to run very rough, like it’s about to stall unless I give it a lot more gas and then coast until I can get back to higher speeds.
Finally, my TPMS light blinks at start up. I’ve had all sensors replaced and the light keeps coming on. When I’ve had resets done, the light comes back on after 20-30 miles of driving. The reset procedures also don’t match for my vehicle on the TPMS tool. It calls for me to use a key FOB, but my vehicle doesn’t have one, so I have to resort to using the 2009 Chevy Aveo reset procedures to get it to clear. 
Sorry for the long list of questions. I really appreciate your videos! It has me very skeptical of what I buy going forward. What would you recommend for a used small sized vehicle manual transmission these days? Thanks again! Keep up the amazing work!