gmc yukon 97 5.7 vortec driving rough at 30?

[bigT]

hey everybody my 97 yukon 5.7 vortec is feeling funny at 30 mph have been getting a cel for my cat converter i have a slite leak in the exhaust cant really hear the leak feel like a miss at about 30 mph just feel quite shakey at 30 till 45 mph then goes away changed the cap and rotor didnt do it and drove with the fan belt off my guy thought it was maybe the fan clutchs shaking idk what it could be any help is greatly appreciated

 

[bigT]

helppp!!

 

[redset1001]

Shifting weird hard to second then little miss and stutter could be map or tranny speed sensor