About 2 years ago I bought an aftermarket intake with the improved design and installed it myself. The intake fit perfectly and worked perfectly...with NO leaks anywhere. I was VERY satisfied.

But 2 weeks ago, my Mustang developed severe hesitation under hard acceleration. The car basically acted like it was running out of gas and kept misfiring.

My "Check Engine" light finally came on and my code reader indicated a misfire in the #8 cylinder.

This morning, when I pulled the #8 spark plug boot off, I saw that the plug was SOAKING WET with coolant! The hole for the spark plug was so full that coolant ran out of it when I inserted the spark plug wrench!

So, I am assuming that there has been a massive failure somewhere.

BUT WHAT DO YOU THINK HAPPENED?

I checked the torque on all of the intake bolts...they were perfectly within specifications (20 foot-pounds).

I did NOT use Permatex on the intake manifold, per the instructions...should I re-think that? Or should I assume that the intake is cracked or warped? Either way, it looks like I will have to pull the intake and see.