Ford - Escape :: 2002 - Blown EGR Valve / CEL Came On And Rpms Would Run Very Low

I will try to make this short but still involve all necessary information. I was driving on the highway last Wednesday when my cruise control went out and i couldnt drive over 25-30 mph, my check engine light did not come on when this happened. I managed to limp the car very slowly about 2 miles down the highway as that was the nearest exit. I took the exit and when i went to "accelerate" at the light i got a loud whooshing sound from under the hood. I pulled into an auto repair shop and found the EGR Valve had a hole blown in side.

Several hundred dollars and several hours later the shop put on a new EGR Valve and had cut the lower cat converter of the car and run a straight pipe where it had been. They said they believed the cat got clogged and built up enough pressure to blow the side out of the EGR. The car ran fine like this for a few days while i waited on my brother in law to gut the cat so we could replace the cat shell as to be within the law, as it is illegal where i live to remove the cat. We gutted the cat and cut out the section it was originally and put the shell back on. The car ran ok for a few hours but then i stopped at a gas station and the check engine light started to blink and the rpms would run way low. When i say low i mean around 1000 at 55mph and would idle around 250, if i put the car in neutral it would idle around 500 but that is still low. What i could look into as the cause of this issue?