First off love what you do and how you love helping people. Thank you. I’ve learned a lot off watching your videos. 

I acquired a 07 Chevy 1500 with a 4.8. Mileage right below 300,000 miles. It was my dads family/work truck. He maintained regular maintenance. My brother needed a vehicle so he donated it to my brother. He drove it for maybe a year. About 2 months ago it over heated on him. Thankful he used his head pulled over allowing it to cool down several times. I did pressure test, and the and tube with blue liquid. Everything was good. April 16th 2021. The vehicle I had was totaled. 99 Chevy 1500 4.3 140,000 miles. Ran like a champ for the years and mileage. 😢 Now jumping to the point. I’ve changed the water pump, thermostat, coolant temp sensor, radiator, all the hoses, fans, power steering pump, idler pulley. A lot I know. I have the cooling system running good now. Yesterday letting it idle with the ac on. While I was trying to get a door latch to open. The truck randomly died. I cranked it back up and died again. I put my code reader on it and it’s said power brake bust large vaccum leak and lean on one of my banks. I changed my mass air flow sensor the day before also a fuel pressure sensor. Now I just don’t know what to do. Any advice before I go crazy?