Two part question. First is the blazer falls flat on it's face when I push on the gas. Doesn't do it all the time. I push on the gas and it stalls out and won't go then it spudders and takes off like nothing is wrong. I replaced the following Fuel pump ,spider under the intake all of the exhuast.
Second, All the 4x4 lights on the switch come on and it feels like it is binding up but will drive. Feels like it's in two gears at once. I don't push anything it does it on it's own. I drive for a while then it clears up until the next time it acts up. Doesn't happen in the warm weather only when it's cold out. Checked the thing under the battery and it works fine. Looked at the vacume switch under the car and it's fine. thanks for the help.

Foegot to say it's a 2000 4x4 blazer s10

 

Im NO EXPERT! Is it throwing any codes???? Check and see if any are stored. Spray clean out MAF- Throttle sensor as well as throttle body needs cleaned. That's simple and cheap. 2 Four wheel drive. No idea Welcome and im sure this will be moved to approiate spot

 

*Moved to '2nd Gen Tech' section*

 

First issue sounds like a fuel delivery problem. Check fuel pressure and leakdown and post the results.

Second, the 4WD switch on the dash has 3 buttons, is that correct?
When you checked the vacuum switch, did you notice any fluid in the lines when you pulled the connector off?