Mike hayward

my son and I recently had to install a new were engine in his 88 Toyota 4 x 4 truck The original 3.0 engine blew up so we installed a 88 3.0 with 160,000 km on it. Engine seems to run fantastic but idles at 1400 and have terrible gas mileage. I believe we have screwed something up during the install perhaps a vacuum line or sensor not working properly. Can anybody help ? also does anybody know where the two vacuum lines go that come out of the ported vacuum switch in the manifold at the back of engine ?