I replaced 2 vacuum lines on my '99 blazer. I had to take the breather assembly off to get access to the rear of the manifold. I unplugged the MAF and another sensor just behind it. (what is that one anyway?) When I put it all back together and started it up, it seems to idle fine except every few seconds the rpm's drop for a second, like it's going to stall, then it goes back up to normal idle. It keeps doing this and even when I drive it, it seems hesitant to go from a stop. Anything?

 

I just wanna bump this cause I really need help.

 

Are you sure everything is connected back up properly? Have you double/triple checked everything you messed with?

The sensor behind the MAF is the IAT (intake air temp) sensor.