89 mustang start the car up and stalls right off

ok i've been trying to figure this problem out now for a couple of weeks. the car starts up fine, runs for maybe 2 or 3 seconds and then stalls but will start right back up without hesitation. if i play with the gas the car will stay running but as soon as i let my foot off the gas it stalls out. i changed a whole bunch of parts like the TPS, the EAC, the MAF, i checked all my vacuums really carefully for leaks, they seem to be all ok but today i found this relay under the hood passenger side by my air filter box and if i shake that relay i hear that its shattered inside. i think its the WOT cutout relay. what does that relay do? also if i would try to leave with the car its like something makes it cutout and jerk. all this started ever since i changed my motor before it was fine. its a 351w with a super victor intake converted to fuel injected. i love fuel injected but if i can't find my problem i'm about to slap a carb on it. any help or suggestions would be appreciated. thanx