PI Intake swap problems

Hey all, been a long while since I've posted, however I'm in need of some advice and such. Anyhow, my NPI intake on my 98 GT was warped and needed to be replaced so I figured I'd go ahead and do a PI intake swap.

So I've done the swap and I'm in the testing for leaks phase and I'm having problems. I took the intake to a machine shop to have the 2nd hole drilled and tapped for the 2nd coolant sensor necessary on my car. They did a nice job as it looks factory and all. The damn thing leaks though, I've wrapped both senors with teflon thread tape, the one on the left side which is already tapped on the PI intake doesn't leak, perfectly fine.

The right side however does, so my dad and I figure we'll unscrew it retape it and use the RTV around it to prevent it from leaking, no good. We unscrew it again clean the area off, clean the threads off and then retape and put a little RTV around the threads and screw it in and put more RTV around it. Just got back from a little more aggresive driving, not WOT, and it's still busted through and leaking. The only thing we're thinking of now is to use some JB Weld epoxy to pretty much cement the sumbitch in there. Curious if you guys have any ideas on wtf might be causing this thing to leak here. We of course let the RTV cure overnight every time we applied it as well.

We have a 2nd leak as well, it's a rather small leak that drips down onto the driveway at the back of the engine, around the bellhousing area I'd say, after the car has been driven around a bit. Was wondering if you guys have any ideas where this one might be coming from.

Have a 3rd leak which is the thermostat housing itself is leaking, we really just found this one now so I'm not too worried about it yet but figured I'd mention it.

Here's the other problem that I'm not liking either. When driving around today it felt really choppy. I'd try and get on it a little and it pretty much hesitated, shook a little(best way to describe it), just felt like the power wasn't there at all and if it was I was having to fight her to get going. Any ideas what might be causing this? Computer relearning? Another leak of some sort?

Anyhow I appreciate you guys taking the time to read this and help us out with whatever you have. Needless to say I'm both frustrated and disappointed at the same time.

hmmm, you may be right on the spark plug idea. part of the original problem with the NPI intake was that coolant would slowly find it's way into random spark plug tunnels and I'd have to end up cleaning them out. I'll have to check that out as I'm gonna have to do a small bit of disassembly to get the area cleaned up again. There's still some coolant left in the valley, and after checking underneath earlier, there was no dripping this time. Maybe it was just left over coolant, but we'll see as you just have to keep checking. Good idea on replacing the o ring gasket, they're cheap anyway so hopefully that'll help. We'll see how this all turns out tomorrow, thanks again.

I tightened the intake bolts according to the Haynes Manuel sequence to 20 ft-lbs with a torque wrench.

After pulling all the spark plug boots, there wasn't any coolant in there to begin with, but just to be sure i cleaned them out again anyway. My dad then crammed the boots with dielectric grease and we reseated them.

We used new PI gaskets and hit temp RTV according to these two guides I found.
NPI to PI Intake Swap...

How To Install A Mustang PI Intake - Installation Instructions at AmericanMuscle.com

In terms of cleaning the mating surfaces we used a gasket scraper and then some brake cleaner from Advanced Auto Parts and that cleaned up a lot of the black **** around the intake ports on the heads.

For the sensor we've talk to our neighbor who's a plumber and he recommended a good product to try and keep the threads sealed. We'll be trying that tomorrow after we pick up the 2nd component of it.

Aside from this info, we'll just have to play the wait and see game until tomorrow when I'll have more information. Again, thanks for the help so far.

So as an update to this here fiasco. It looks like the tap that the shop did on the manifold was a bad tap as our plumbing neighbor noticed the sensor was cocked/tilted a little. So we'll just be useing some JB Weld epoxy on it to pretty much cement that in there.

New thermostat o ring fixed that particular leak, so we know we just need a new o ring each time we open the housing I guess.

The hesitation issue is gone, guess there was moisture somewhere in the tunnels/boots.

There's still a leak in the back of the engine somewhere as there was a nice sized puddle on some cardboard we put under the car overnight. Seems like it was slowly dripping from the driver's side as that's what the puddle pattern indicated. I plan on ripping this apart and putting it back together starting tomorrow. However, before I end up doing that I was wondering if you guys still have any clue what it could be? Not enough RTV in the water jackets perhaps? Also, since I'll be taking the intake off, will I need to use a new set of intake gaskets again? Or will I be able to get away with reusing the current PI intake gaskets I have on there?

Once again I appreciate you guys taking the time to help me out here. If you want some pics I can take some tomorrow after demolition...errr, removal or the intake so you can let me know if I'm doing it wrong or something.