z28muscle51

I have a 1995 Z28 with the 6 speed manual tranny, 350 etc only mod is cai. When im doing anywhere from 70-80mph, my car will suddenly act like its bogging down, loses power, and starts to rattle, from the back of the car. If I give it a little gas, it will eventually stop bogging and start accelerating after 4 seconds or so. It always does it in 6th gear, and sometimes does it in every gear. Lastly, when I idle in 1st gear (through a parking lot etc...) it makes a loud "pop pop pop" sound, around what i think is the transmission. Does anyone know what this is or how to fix it? Thanks
__________________