Q: I've got a 01 chevy Silverado extended cab z71ive had it for about 8 months as soon as I bought it realized it burned way too muc

01 chevy Silverado extended cab z71ive had it for about 8 months as soon as I bought it realized it burned way too much fuel took to shop an was told knock sensor an o2 sensors need replacement as well as previous owner bored out both cats an put back on idk if that could add to thelose of power an fuel incre uased use. But now she's been parked one morning going to work I started her up like I do every morning sat fir a moment then put truck into reverse an nothing then i went threw all gears an nothing happend. Sat fir a second tried it again and when I put in revers this time I mashed gas an it jerked me hard as crap an same in drive maybe heard a lil humming noise and vibration when I got on the road it seems to have quit well I got off the interstate an I heard a loud chain noise it sounded just like a big metal chain dragging on the pavement an then she would vary go at all when I mashed gas basically Fred Flintstones it to parking spot an then she wouldn't even lock intoanything

My car has 189000 miles.
My car has an automatic transmission.