2002 Hyundai Elantra

Engine Performance problem
2002 Hyundai Elantra 4 cyl Two Wheel Drive Automatic 133, 00 miles

My car is acting very strange. The engine wants to quit on me. It keeps stalling. When I am driving, the engive willl cut out for a few seconds and if I keep the gas on, it will like restart. It is hard to explain but it is almost like it shorts out. I have had cars not idle for me but this is different. It just dies
even when I am applying the gas to it. Doesn't matter how fast or slow I am going.

We recently removed the catalytic converter because it was plugged and just put in a straight pipe. Could the two be related somehow?

Thanks for any help you might be able to provide. I know it is kind of vague but not sure how to explain any better.
April 14, 2010.

Inspect and test all the following listed below and get back with some results

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard.

Apr 14, 2010.