I had a little vacuum leak when ever I stepped on the brakes (you could barely hear the engine die down then up, also happen real fast). After I put the new o2 sensor in this happens when I hit the gas then let go (it happens right before it hits idle). But if I hit the brakes my engine comes close to stalling. Anyone know if this sounds like something else. I almost sprayed two cans of engine start and cannot find anything. I also sprayed it once in the intake and it made my idle die down instead of rise, why would it do that?
Any help is greatful because I have work in the morning.

Thanks,
Mario

 

Sounds like you have a bad brake booster.(not really related to the O2)
Check where the rod goes from the brake pedal through the firewall. It sounds like you are loosing engine vacuum which would cause it to almost stall.

 

If the brake booster is sucking air in it could cause your engine to stall. Also double check your hose clamps, I had a similar problem one time and it was just that I forgot to put my hose clamp back on and once I did there were no more probs.