Help! TJ surging out of contrl on start...4000rpm+

I need help TONIGHT, cause I need to tackle this tomorrow morning (Jeep is stranded at a buddy's garage).

Here's my story. TJ was running fine, but I failed inspection due to a crack in my exhaust manifold. I spent the whole day replacing the exhaust manifold with a new one (Borla). The install went fairly flawlessly... but when I started the Jeep it just surged out of control. I had to cut the ignition. Happens with the throttle linkage off... its definitely not a gas-pedal thing. The throttle plate never moves (unless I reattach the linkage and press the pedal, of course).

What's scary is that I can't starve the engine. The put my hand over the intake I feel suction but the engine just keeps going higher and higher regardless. I have to cut the ignition after maybe a full second, for fear of ruining my engine.

All connections appear right, and no obvious leaks.

If my intake wasn't attached flush (looks right, and "felt right" during reinstall).. and had a big leak... Would this be the behavior I'd see? How does it get the extra gas?

I'm really freaked and don't want to tow or anything (just spent $400 on the part alone!). Any help is greatly appreciated.

Thanks,

Sam88Jeep
(Jeep is a 98 TJ, Sahara 4.0)