If it's cracked, I believe Ford has extended the warranty on this item.

http://www.fordmanifoldsettlement.com/index.html

It could be a hairline crack that only appears under pressure ie:when the car gets hot.

If it's NOT that, then I would go to Ford and get the stock t-stat and O ring.
Ask the parts guy to print out the diagram, or at least show it to you so you can see how it's installed.

You should not use gasket maker etc because it will make a mess and will fail.

 

you over tq'd those 2 bolts when you put it back together, cracking the IM, get a new IM

 

Ouch...

Torque wrenches help stop the breaking of stuff on these composite motors. I had a stock 00 intake (plastic) crossover. Make me an offer as it was a recent install and I pulled it off when I bought my GT in Feb installing an aluminum one.

 

Jegs did have them for 199.00...which was a FORD intake,,not some aftermarket(POS)...you'll need new intake gaskets...and maybe a set of injector o-rings(I replaced mine )and an egr gasket if you tear it ...Also the factory alt bracket will not work with the new intake design,,need an alternator bracket from an 02 mustang(4.6 GT)....ordered mine from ford and it was 18.00 bucks.......Warranty for 7 years or 70k...I think,call and ask,,never hurts.......

 

I'm a little confused on what exactly the crossover is. Does somebody have a picture of it? The place i took it to torqued everything to spec. It's not leaking at the top where you tighten the bolts. It's at the bottom where it connects to the block. I'll try and take a pic of it.