just had new exhaust installed on 89 13bna had leak for about 2000 miles, at second catbac. changed new plugs, air and basic upkeep. now backfires after 4rpm in all gears and idles pulsating w/o ac on. no upgrades yet want to k now if its time for a shop stop,also seems to be burning oil, no leaks though right at 60k all original except for exhaust

 

Backfiring - its a rotary thing....get used to it. but just to be safe, check your timing, TPS and your BAC valve. Most of my backfiring was cured by setting my timing to spec.

Oil consumption - our engines are designed to burn oil. Its injected along with the gas. Should burn a quart or two every thousand miles or so. How bad is your car eating oil?

 

yes, these cars are more prone to backfiring than most, but that doesn't mean they should all backfire all the time.
something, or a bunch of things, on the car is just out of adjustment. it's probably not a big deal, but there is surely some reason it is backfiring. a perfectly adjusted car will not backfire...