so i had a MAP ECU installed on my car a bout 6 months ago first off i was amazing results i saw a huge hp gain at the wheels, from 238 to 285 at the wheels on the stock exhaust and turbo. since then my car has developed a problem with stalling out. it doesn't do i all the time just kinds sporatically with no common point to the stalling, although about 70% of the time its after i exit the freeway but it still does it other time about the only common factor is that the car has to be driven for about 20 30min before the stalling occures. after it stalls i rev the car to about 6000rpms and it seems to not stall untill the next time im at a light where i rev it again. i was told that this could be the result of a clogged cat on my Down pipe seeing as how in still using the stock exhaust, money flow issues have prevented me from gettin that larger exhaust. is there any way to test to see if it is the down pipe like i was told or should i start searching else where.