Tahoe rear E brake
Tahoe's have a know problem of the rear brake backing plates rusting out and causing noise. The backing plates must be replaced. Several people seem to find the E brakes don't work after they replaced the backing plate. I've always found the problem is that they lost the pin that is under the adjuster pad. This video should help you identify if that is your problem.
How to find a Small EVAP leak without a smoke machine
Small evap leaks are the hardest to find. Using a smoke machine is very commonly how we find them. However, if you don't have a smoke machine, you still have your thinking machine. Use your Critical Thinking to understand the system and find the leak.
LLV Windshield leak
The windshield usually leaks from one of two places. Either around the entire windshield because the sealer has broken up, or more commonly where the side mirror bolts on. This is is hard to see without a mirror & flash light. But check it before you replace the windshield because if it's the source of the leak, you'll still have a leak even after replacing the windshield.
Why we replace the Intake
Replacing the intake is actually the best repair. To replace only the seal would cost more because of the added labor. The screws holding the disks usually twist off and have to be drilled and tapped, and find new ones,then the shaft would have to be driven out which will flatten it's end, then both openings would have to drilled and sleeved, then a seal located & glued in, then all reinstalled. After all that you would be only replacing one runner shaft and not the other bank shaft seals. It would be labor intensive and you would still be risking leaks from the vacuum check valve, hoses, vacuum motors and solenoids. With the additional cost for parts and labor it is much more cost effective to replace the complete intake.