91 5SFE Blowing off egr hose.....

So I bought a 91 GT 2.2L 5sp coupe. The PO had to get it smogged, and it passed no problem (NOT). Aftter owning it for a while I realized the car was not well maintained. Air filter was black and caved in....that was my first clue. Cracked air tube and unplugged egr elec line told me the PO had a friend at the smog station. So, I have replaced spark plugs, air filter, fuel filter, valve cover gasket, etc.
But the other day I was driving along and the car started bogging and sputtering and lacking power until it blew the hose that runs from the egr valve to the vacuum modulator! Loud air noise showed me where to look. I remosed and cleaned egr..all o.k., vacuum mod checks out good with a clean filter. Replaced vacuum lines (all that where visible and reachable from top. Cleaned throttle plate. Chedked throttle body vacuum ports, o.k. Dont know anything about cannister and other emmision items...not much in Hayes manual. Is there a way I can figure out why there is so much back pressure on that line? Any help would be greatly appreciated. I have been reading posts here for a week tring to figure this out.