I was riding down the interstate at 1130 PM, low 70 deg, about 70 - 80 mph in 5 th gear and i let off the gas completely to slow down a tad and BAM and i'll i saw in rear view mirror was this light,acutally i saw it out of all mirror and window. So i tried to do it again,and couldn't , but aoccasional little pops. So i get home put the car in nuetral and idle is jumpy 200 - 600 when my normal is 1000 rpms. Car is sounding like it's sick. Shaking and puffs of black smoke out of the exhaust. I waited 5 min started it back up. Everything is fine Vac 18 on boost guage and 900- 1000 rpm on the idle. So the next day i drive it, i'm getting studders through the rpm band 1-3 to about 4,500 rpms in each gear. I go 2 blocks stop at light,and the idle is doing the jump between 600- almost 0. So i pull over car isn't stalling but sounding like it's gonna,with black smoke coming out again. On the way home it backfires about 5 times,the loudest dam backfires i everheard. I'm not gonna be surprise if my muffler is split wide open. Anyways i checked the Map sensor hose. It's attached to the sensor and to the engine . What else could cause this problem. This doesn't mean my engine is toast, just a rich issue i hope.
Mods:
Blitz intake
M2 downpipe
midpipe
Greddy PE exhaust
HKS Fcon fuel computer

 

if the obvious have been checked, it may be timme to make sure your injector o rings arent leaking.
John