I would start with the ignition,change the points,condenser,cap&rotor,plugs and plug wires,if it still has a prob. check to see if U have any bad fuel lines because if ther R any cracked 1s it could start sucking air insted of fuel. Also check your timing and make sure your floats are set right because it might B starving 4 fuel but I think its in the ignition,if U can afford it U might aswell replace the coil as well,because it could be going bad also.
I would not go out and buy anything until you can identify the problem. Being mechanically smart is great, heack a 12 year old can be mechanically smart, but it takes a smart person to identify the problem then start buyign things. First run fuel tests. run a pressure test then a flow test for the fuel lines. Sounds like a fuel delivery problem to me, but it could be ignition so then check, not buy, but check things out. If it does need replacement due to time thats different, but i hate the word buy when the problem is not yet identified.
O.K. look,U just got the car right? Trust me when I say this, buy the simple tune up parts, they don't cost that much, install them as per instructions,once youve done the basic tune up,you are now starting w/a new slate and knowing that sure makes things easier.Sure U can perform all the test's U want & the chances R that you'll cure the prob. w/a tune up & save a lot of time because one day you'r still going 2 have 2 do this so do it now. PS, dont wait a minute,seize the day!
with the rpm bounce i know from experience its the points. nuff said with that subject. do yourself a favor and make this simple little conversion to a early 79 or 80 ZX distributor and eliminate that problem forever. must have a 12-80 module. its wasy and cost effective and you no longer have to deal with those horrible points systems
ive done it to mine and love it. the electronic distributor gives you a lot to notice in driveability.