89 K_2500, 5.7L Gas. Map sensor has two vacuum lines connected to the back side of (facing firewall) it. One goes to the EGR valve. Please tell me where the other one goes. I have looked, looked, etc., cannot find it.

 

Same here! It was like that when I bought my truck 9 months ago though

 

The MAP sensor only has one vacuum line that goes to the back of the throttle body. Are you sure your not looking at the EGR solenoid, if so nothing goes to 2nd vacuum port. Just one on the back to the EGR and one on the front which goes to the front of the throttle body.

 

You're correct. It is the EGR Solenoid. Sorry for not responding sooner.........been busy with other things. tx...........pop