[87 foxbody]

Hey guys I'm new to the forum. I joined because I'm tryin to get my mustang up and running right. Here's the story...

I bought my 87 fox about a year ago with the stock 302 with a speed density setup. I drove it for a couple weeks and the oil pump went bad in it. I decided to throw a motor I had from one of my previous foxbody's in it because it is a pretty fresh motor. I pulled the upper and lower intake off the old motor and put it on my other motor (its a roller fox motor aswell) and slapped it in the car. I know that motor works off speed density because I had it running in my 82 fox. The car starts up and runs but its gettin way to much gas. It has headers and about 3ft of 3in pipe off each header, and the smog pump is deleted. Other then that its all factory. I did a vacuum test on it and at a idle its only pullin 8-12lbs of vacuum. I went over my vacuums and cant really find a leak. I've been debating changing it over to maf. If I do that will it fix my problem?? I have the computer so far. Just need the mass air flow sensor and the 4 wire kit for the computer. Anything else I would need?

Any help would be really appreciated. Thanks

[fogged306]

What cam was in the new engine that you put in? Is the valvetrain set up properly? 8-12" of vac is too low for an SD system to idle properly. From what I understand, lack of vacuum at idle will cause it to run rich because it thinks more air is going through the intake than there actually is. You need a speed density friendly cam in there, and your valvetrain needs to be set up right so your valve event's are correct, otherwise you could be bleeding off vacuum at idle.