G'day everyone, its been a long time since I've been on here but here are my issues:

A while ago I pulled my engine and transmission out. Lets not go into details about why but now that is all back in it runs better.

Now however, my fuel efficiency is crap, it has gone from 500-550 a tank to 350 if I'm lucky. Now, what could be the issue here?

Well, I at first believed that it could be the O2 sensor or the MAP sensor, but they are both plugged in and they weren't knocked around during the process.

Here's where I think the problem is now. After putting the engine back into place, i saw that there were 4 connectors to the loom:

-A round one
-A square one
-A roundish squarish one
-A rectangular one

I also re-plugged in the vacuum lines before anyone says them too.

Now my car is a factory manual so I've plugged all but one of these in as I spent a whole day looking for the other end of the round connector and couldn't find it. After calling a wrecker they told me that it isn't plugged in on the manuals?

Is this true? If it is then I'll be using fraser's diagnostic tool. But, I don't believe them these days and I can't think of any other things that it can be. I looked on my mate's (fast futura) car and indeed this isn't plugged in but his is an ED with a conversion, not factory and it was done by very dodgy people.

Please help me.
Rem