because you have an engine misfire.most likely the DI cassette is faulty. (Ignition)
A bad throttle position sensor, on your 1991 Saturn, will cause the engine to run rough when it is idling. The engine will run normally at higher speeds.
your engine will sound rough while at idle speed and your gas milage will start getting worse. it also might start to backfire and make a little more noise than it normally would.
Poor maintenance and/or bad ignition coil.
You have a few things to check, first off a backfire is usually associated with a timing issue, you would notice a difference in ow the engine runs, it will lack power and be rough. Next a backfire requires unburnt fuel, so check the ignition system for problems, bad or incorrectly gapped plugs, bad wire, and if it's older look for a cracked distributor cap or worn rotor. Then look to the fuel system, it may be getting more than it can burn. Lastly valves, you may have a bent one, or one that is not opening or closing completely.
The Right Front ABS wheel speed sensor is also used as a rough road sensor to assist the knock sensor in dectecting weather there is a knock from engine or bump from the road in order to adjust the spark and fuel.
A timing chain, that needs to be replaced, can cause your engine to run rough and lose power. A broken timing chain can cause significant engine damage.
Car will run rough ,backfire and you may be able to here it rattling.
the check engine light is blinking and my 03 Nissan exterra is running rough
More than likely ignition timing..
Only rarely is the adjective "rough" preferably used as an adverb (e.g the engine still runs rough). The usual adverb is "roughly."
because that's kind of a big engine