Installation of a '95 3.0L OBDI Intake onto a '99 3.2L OBDII Motor

First thing is to remove the stock manifold.  Do this by removing the fuel rail cover (two bolts). Once it is off you can bleed the fuel pressure left in the rail by opening the valve at the front and use a small screw driver to depress the pin.

Next start removing the ASC Throttle body then the main throttle body.  There's no reason to disconnect the linkage, just set it aside

With the throttle bodies removed, you can remove the two bolts holding the fuel rail down.  Then pull the entire fuel rail and injectors back out of the way.  I didn't remove the injectors from the rail but you can if you need the extra clearance.

Next remove the nuts the attaching the manifold to the head. Also remove the two bolts (one in the front and one in the back) that attach the manifold to the support brackets.  Now carefully remove the manifold. There will be three vacuum lines (two small ones and a larger one) you will have to disconnect from the manifold to remove it.  Also on the bottom of the crank case vent (big round thing under the front of the manifold) disconnect the oil drain line.  Disconnect the IAT sensor harness and the Idle speed controller harness.  With all these fitting removed you should now be able to completely remove the manifold.

You engine bay should now look like this

Now remove the Idle control valve and the crank case vent assemblies off the OBDII manifold.  Remove  the IAT as well.  As you see there is no place to mount them on the OBDI manifold, this is where the fun begins.

On the OBDI manifold, there is one large fitting in the middle right behind where the throttle body mounts with a smaller fitting on the side.  At the back there is a small vacuum fitting and a threaded hole in the front.  We are going to use the middle and back fittings later.  You need to plug the front threaded hole.  I had an old oil pressure sender lying around and the threads matched so I use it to plug the hole.  

Take the Idle Controller and remove the rubber O ring off the end.  You will notice that the metal pipe is about one 5/8 dia.  do the same with the crank case vent.  Now you will need some 5/8 hose.  You will also need a 5/8' tee fitting and a couple of 90 deg elbows and hose clamps.  I remounted the idle controller to the rear support bracket.  Had to trim off a bit of the bracket to fit.  There's a mounting hold on the support bracket that work well

As for the crank case vent.  You could try to mount it to the front support bracket but I used good old zip ties to hold it in place.  Make sure you reconnect the oil drain

As you see in the next picture,  this is where the 5/8 tubing and tee fitting come into play.  basically connect the tubing to the crank vent and the idle controller with the tee in the middle 

Now we have three more vacuum lines to deal with.  The line that runs to the fuel pressure regulator (hard plastic line that runs towards the back of the motor will connect to the single vacuum fitting on the back bottom of the OBDI manifold.  As for the other two you will need a vacuum tee to connect them together and then to the fitting on the side of the large connector that goes to the manifold seen above. Now reconnect the plug to the Idle controller. The IAT sensor will be relocated into the rubber elbow that connect the throttle body to the HFM.  We'll connect this later. set the connector aside or you'll lose it under the manifold.

Next set the OBDI manifold into place and connect the vacuum lines.  You should only have two connections to make. the one big one in the middle which has the smaller line already connect to the side and the vacuum line for the fuel press regulator goes on the bottom back.  The vacuum line for the brake booster is in the same place on both manifolds.  Go ahead and bolt the manifold to the head.  As for the support brackets,  will a little help, they will line back up.  You will need to pry/bend them about an inch or so.

Now for the fuel rail.  A slight mod need to be done first.  on top of the rail are two holder for the O2 connector plugs.  The one on the back need to be removed.  Use a dremel or a hack saw and remove it.  When reinstalling the fuel rail the fuel lines on the back will hit the OBDI manifold so VERY CAREFULLY bend them out a little bit to clear it. Next you see the mounting hole don't line up.  you will have to make a simple little bracket to bolt the fuel rail down. See the pic below

Next up is the Throttle body.  Since the OBDI and OBDII gaskets are used in a different manner you will need two gaskets.  Take a razor blade to one of the gasket and cut it down the center so you now have two rings. Place one half of the gasket in the manifold and the other half in the throttle body.  Take the other full gasket and place it between the throttle body and the intake and bolt the throttle body on.  replace the AST throttle body next

Now lets mount the IAT sensor in the rubber elbow.  Just drill a hole on the bottom and pop it in. keep the hole small enough so it seals good. reconnect the harness plug to it. 

Reconnect anything else you may have disconnected and you should be ready to go.  

As for the fuel rail cover the OBDII cover will fit but it sticks up a bit.  I went and bought a '95 cover ($26 from dealer) and it didn't really fit any better.  The problem is the OBDII fuel rail is different.  I cut down the mounts on the '95 cover and it fits better, but not perfect.  The pics are of the OBDII cover.

I think I covered everything.  You will need to make a trip or two to the auto parts store for vacuum line and fitting but other that that the installation can be done in a afternoon.