Here's a couple videos to check out. Your past problems may have led to degradation of the cat, and I concur with JC, if you have to replace it, be sure to get an OEM one from a dealer. 1. (Less technical) 2. (Highly technical, but pay attention)

 

watched that one already,the light has not come on yet and I went twice the miles that made it come on...cross fingers.

 

Cross

 

it went back on...got some catclean to try..

 

have to get down to a 1/4 tank first..figures I just filled it up.

 

got the elm 327,pretty cool I need to try diff apps on it,can check the o2 codes,the thing says I have 1 02..but I have 2..

 

I have the Torque II app. But I hear there are others that give more info.

 

Ltft says 16% hmm i thought i fixed vacuum leak .. They say 10 is no big deal,20% will throw a code..i guess im in the middle.. Looking at O2 sensors 1 looks good 2 im still figuring out what it should be like the video..

 

The LTFT needs to be resolved 1st. As you know that would ideally be 0%. Looks like you still have vacuum leak you need to fix, then check the O2 sensor. The sensor reading wont look good until the vac. leak is resolved. Check for cracks in the tube between the EGR and manifold. Might take a smoke test.

 

O2 1 looks normal as it should be O2 2 is reading high 6-7 volts, goes down reving it up,. Is that normal.. Im getting the hang of this... I fix computers for a living . So its a new learning curve.. Grew up in a car dealership in the 60's