What is this and what if the bottom hose was disconnected.

 

at a guess i would say it is a variable vacuum regulator for the efi, after that i do not know it's fuction but i guess it is important

 

the thing with the screw on it is the idle up adjustment for the a/c system. without looking at mine and knowing what the hose connects to on the other end, id say with the hose not connected it might not idle up with the a/c on or it might just have a big vacuum leak all the time.

 

Would it be a reason why I am not passing smog? Would it make the engine run rich?

 

Your truck must not have power steering. As that is where the capped line would go. No, it would not make it run rich at all. Check you r02 sensor and TPS adjustment, maybe valvres and a basic tune up will cure what ails ya...

 

Thanks Xs5875. I tested the sensor and it is good. I just needed it to be tightened a little bit and I ended up cracking the screw but it still is in the same position. I used this webpage for testing. Toyota 22RE Throttle Position Sensor
The resistence didn't open until around 1mm. I also noticed the throttle is sticky and it takes a good push to get gas flowing then it is not sticky until I let it sit for about ten seconds. I will test the o2 sensor next. How do I go about testing it?

 

I don't have power steering. This is true!!

 

Can't really test them. I'd replace it. You have any codes?