1997 Mitsubishi Diamante - Engine shuts off during deceleration/stops.

What is your question?

The car runs fine at normal speeds but when I slow down (usually at stop lights) the engine cuts off. When I let off the gas, the brake pedal loses some resistance. The car also seems to lose power when accelerating from a complete stop. All of the symptoms tend to point me towards a vacuum leak of some sort. I was wondering if anyone had similar issues and what other things I should be checking other than the throttle body lines. - I read in the Galant issues section that there were cases of a failing Idle Air Control Valve that were causing similar issues. Is this common with the Diamante as well? I recently had the exhaust replaced and they removed the catalytic converter but I don't see that being the problem as the low idle was there before replacing the exhaust. - Any and all help would be greatly appreciated. Thank you all very much! -Frank