Hyundai Repair: 99/00 accent GL SOCH, throttle position sensor, crankshaft position sensor

Question
QUESTION: my buddy has feb 22, 2000 build accent GL SOCH motor. stalled out and died on the over. towed it to the house, let it sit for a couple of days, to save up the money for repairs, went out to the car, started right up and drove home. stalling, spitting and sputtering, lack of power. thought that a tune up would help, changed plugs, wires, oil and filter, all of the belts. could not get a fuel filter in town, so i waited for that. got the car going, idles great when warm, but like crap when cold. slight press of the accelerator and the stall out begins again. used over two cans of throttle body cleaner, had the injectors cleaned (professionally), checked the throttle position sensor (TPS). he said that he was going to take the car home anyway, and about 10 miles from my place the car died. we to get him with the trailer, towing it home. once I got it here decided to wait till the next day to work on it. guess what, it started up. he tried to leave again, making about two miles this time. towed it home (again) waited till the next day, again, checked the coil packs, wires, plugs, etc but nothing seems wrong. please help me stop pulling out what little hair i have left

ANSWER: Hello AC,
Stalling and rough idle is telling me you might have a bad Air flow meter. Remove it and see if it has any dirt or oil on it. Also for the no start problem; do you have spark on the spark plug wires when no start condition occurs? If you do not have spark, crankshaft position sensor might be giving up.

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QUESTION: ok, check the spark when no start, and no spark. after letting the car sit overnight, it starts right up. one issue that i forgot to address in the orignal question... the flex pipe near the exhaust manifold was rusted in two, i replaced it, but that was during the routine tune up. one of my buddies in the car business seems to think that maybe the catalytic converter could be going out, when it gets hot the honey comb expands, choking the engine, and when cold contracts, but that does not address the cold idle stuttering issue.... will check the air flow meter in the morning. if it has dirt and oil on it, is it safe to clean with carb cleaner? thanks

Answer
Hello again,
You can clean the air flow meter with a carb cleaner. Just make sure you do not damage the honeycomb metal grill. When you have a partially or fully clogged catalytic converter, it effect the idle and also you feel it mostly at acceleration -cold or hot-. Also you should have a check engine light that show an insufficient flow at exhaust system.