Advice on a 2000 blazer with 130k that is new to me:

no codes are being thrown at this point

#1
I have no little to no cabin heat, thermostat and water pump are new and the truck consistently stays one notch below 210 degrees. Also there are floor to face to defrost air direction issues. I am pretty sure that they both could be a vacuum line prob, and I am about to dissect the dash and trace the lines. I have the auto fan/temp control unit in this one. Am I on the right track with this?

#2 (most serious)
I have what may be a transmission prob but I am posting it here because after reading around, the vacuum and 4wd systems seem to be related. Between 5-30 mph, very intermittently, I get drops in power and drops in rpm, as if the truck is about to stall. Past second gear it runs fine. I want to say that this only happens when the tranny is hot, but I am not sure.

#3 (Unrelated?)
I also have a mild fuel gauge bounce. Mild as in my safari van used to go ALL OVER THE PLACE, then the fuel pump crapped out (PITFA!!!) Is this my fuel pump giving up?

Any advice is much appreciated

 

First determine if you have flow through the heater core. Remove the return line and check to see what is coming out of the heater core. If it is plugged up you can back flush the core to see if you can get some of the junk freed up and out. Use a hose and water pressure from your house to back flush. (Opposite direction of normal flow)

Vacuum lines are like this: you have one going to the 4x4 vacuum valve on the firewall when you push the button inside the switch opens this valve and the vacuum is now present on the line leaving this valve. This line is going to the transfer case and a return line is going to the actuator under your battery tray. You would only experience a problem with engine performance due to a leak in the first line leading to the 4x4 vacuum valve.

 

Your 1st problem, +1 on previous post. Just make sure you don't use too much water pressure or you will destroy the heater core. It sounds like you may have a blend door actuator problem, with the air direction being off.

+1 on previous post for your 2nd problem. You may alos be in need of a tune up, plugs, cap and rotor. Use only delco parts, and you won't be sorry. You should also clean your maf sensor with maf sensor spay. Changing the air filter wouldn't be a bad idea. You should see some mpg gains witht the tuneup as well.

Your 3rd problem, its not exactly a sign of a dying pump. My truck has been doing the same thing for over 30k miles. You can try a double dose of techron concentrate plus ( the 20 gallon bottles) corvette owners swear by it, I didn't have much luck though.

 

Here's how I solved my air flow directional problems:

GMC Sonoma & Chevy S-10 Transfer Case Vacuum Switch

A MityVac (or similar) is a pretty good tool to have.

 

Heat is fixed, didn't realize the floor was wet. Spent yesterday and today changing the heater core. The only vacuum line that was split was the black one coming from the engine bay, and air direction also works now.

So for prob #2 seems like you guys aren't suggesting a tranny issue. How would I know if it were a tranny issue?