What could be problem

Sounds like you got some bad gas. May need to replace the fuel filter

Probably they lifters are sticking causing timing and firing problems.... I had the same issues and after cleaning all the build up off the valve stems, lifters, and everything, put it back together with a new valve cover gasket it ran great.....

Could be such a multitude of things.Good news is for that problem 90% chance it is very minor but usually not cheap(small sensors cost a lot).You have to take it to an auto parts store for a FREE diagnostic check. Takes 5 min. and will tell you what sensor,ECU etc... is bad and would cause your particular problem.Spend your $ ONLY on what is causing your actual problem and if another part checks out bad but is causing no problem do not waste your $ on replacing it.BE WISE BEWARE and use common sense.

If the engine oil was full of antifreeze when the intake gasket went bad, then there is a good chance that there may be some cam and/or lifter damage. A more likely cause of your problem would be that the push rods got mixed up when you put it back together. The intake and exhaust rods are different lengths. If this is the case, and you have turned the engine over, there is a good chance that you now also have a bent pushrod and intake valve. The exhaust pushrod is the longer one and if you mix them up, the piston will contact the intake valve because it will not be able to close due to the longer pushrod. This will bend or break the pushrod and bend the valve stem.

Could be a bad converter. I would go to a parts store and have the codes pulled and identified.

This is a good indication of a bad ignition control module. The module is located under the coil pack (where all of your spark plug wires come from) and may be testable. Auto Zone says they can't accurately test this part but it is $100 to replace it.

When was the last time oil changed before this one. Your hydrolic lifters are losing prim. Causes the rocker arms play. So valves are not opening and closing right. eather higher vis oil like 20w 50 or fix the lifters

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An engine is usually not permanently damaged by running without oil for a minute or two. They are often run with no oil pressure for 10-15 seconds every time the oil is changed. It's never really good to run them without oil, but it doesn't usually hurt them if it's only a minute or two. Hydraulic lifters, however, do pump out quickly and make A LOT of noise. If the oil pump fixes the oil pressure problem, you should be fine. Obviously I can't guarantee it, but if it was only a minute, I'd give it much better than a 50/50 chance -- I'd say it is probably more like a 95% chance you'll be fine.

do a compression test. cylinder 3 could have a bad valve lifter or valve.kia sephia dont have push rods.it have a bucket type followers.a intake leak to that cylinder can also cause misfire problems.

you need to double check your timing ound like you might be a tooth off