what is the miles ,you mention the other owner ,is the car new to you ,is it the wavey water light red,I hope your coolant is low ,

 

Yea on the light and new to me they said I need to.adjust the idle

 

can you make a recording for us. utube works on here. it would help allot to hear the exhaust and how it idles

 

A common issue with these cars as they age is the transmission mount. Both the clanking going into reverse and the jump in second could be because of that. Assuming the plugs, wires and filters are all up to date my next go to thing for rough idle is the IAC ports needing cleaned and the EGR not seating. EGR can be cleaned and tested. Head over to youtube and search "Cleaning EGR valve" and Clean and testing IAC.

This is a 3.4 or a LT1?

 

Lt1 inside

 

yes sounds like the guy rocked it before you got it ,,when I got mine I did wires plugs cap ,but waited till the water pump went on that ,as the water pump had to come out to change the opti spark,changed gear oil ,a full tune up ,the tranny if you can get it to stop moveing ,replaceing the the fluid a flush is a start pan gasket ,I would take to a guy that knows tranys before you spend to much on it ,then know if it need a rebuild or not ,it may not ,it may just need the tlc

 

What do you mean rocked it

 

beat on it,thats fairly normal with these cars with the age bye now seems someone may have an some guys think there rockets but there not ,you did not mention the miles on it

 

150k miles ive drove it a few times now and once it warms up itll run and idle under the 1 on the rpm gauge also no matter how long ive drove it if I go into reverse it cuts off unless I use brake and.gas at same time ....it sounds.like it has a different cam in but not sure could just be the idle I don't feel the hard shift anymore either

 

sounds like you may be missing a cylinder, check/change plugs and plug wires. have a look at the opti, its the distributor and is under the water pump at the front of the engine.