TOY: Bad mileage on 22RE

[jguard@xxxxxxxxxxxxx]

Hi. I'm new to this list, so I just thought I'd say Hi! I do have a question 
for you guys though: I have a 94 toyota 4x4 pickup with the 22re. I bought it 
three or four months ago, and previously knew JACK SQUAT about automobiles. 
Now, however, after browsing the web for many months, I'm learning fast, and 
quickly realizing how I want to modify my truck. But first I'd like to get it 
purring like a kitten! I've changed the air filter and given it a tuneup along 
with regular oil changes, but I only get just under 16 miles per gallon on the 
highway, and about the same around town. Is this normal? When I was changing 
out the spark plugs and all that I heard a electric sounding humm coming from 
the passenger side of the engine compartment, right near the firewall. I 
thought this was extremely odd, because I had the negative terminal of my 
battery disconnected. It would humm for about ten seconds, stop, and then humm 
again a minute or so later. Any ideas what this is? I talked to some friends, 
and they said it may be a vacume leak, but I would like a second opinion from 
you guys. Thank you muchly. 

Jesse Guardiani