When your swap the coils over pull out the #4 plug and see if it is fouled or realy dark, if it is it could be your injector. Aonther thing that has me thinking is you said it misses bad when you hit the brakes at idle. Check for a vacuum leak starting with the hose going to your brake booster.
Hope this helps, Dennis

95 Sportage, gone but not forgotten.
98 Jeep TJ, 4" Zone springs with RC Long arms, Ford 8.8", 4.56 gears & Detroit locker rear, D30, 4.56 & Detroit Trutrack front.