stutter

Recently, I started to get a weird grinding/stuttering noise when my automatic transmission shifts. The grinding noise can start from the 5500-6000 rpm range and only happens when it floored. My guess is that it has nothing to do with the transmission and everything to do with the cat being...

ive done plenty of seaching around but long story short im hoping to get some ideas on how to get my car right again, i parked it for about a month then drove it today and it stumbled when i got on it but after i got past 2800 or so rpm it continued to pull. it just kinda felt like it let out...