Anyway, out of frustration and and anger, I reved the engine, and the problem went away. So everytime it happens, I rev the car up to 5000-6000 and it goes back to normal.

P0300 - Random Misfire Detected.
P0301 - Misfire cylinder number 1 very likely
P0302 - Misfire cylinder number 2 very likely
P0303 - Misfire cylinder number 3 very likely
P0304 - Misfire cylinder number 4 very likely

ANY TIME YOU GET A MISFIRE CODE CHECK THESE SYSTEMS:
IGNITION SYSTEM
Check spark plug tubes on four cylinder engines for moisture
Inspect the spark plugs. Are the plugs fouled? Are they the correct specification?
Check spark plug cable resistance (maximum 4000 ohms per foot of cable)
Check for arcing between plug cables (mist the cables with water and look for small sparks)
Check ignition coil. Are codes set for companion cylinders? Check primary and secondary coil resistance as described in the Shop Manual. Use HDS to evaluate the ignition in Signal Wave Forms (see HDS Plot #1). For 2.0L Sonata use the Red lead and back probe the connector at the coil.

MECHANICAL
Check oil level. Is contamination (dirt, sludge, or fuel) present? Is the oil the correct weight?
Perform a cylinder leak down test with the engine cold. Be sure the engine is not fuel flooded. Leakage results should be 10% or less.
On specific cylinder misfire codes, replace intake and exhaust hydraulic lash adjusters for the cylinder that is misfiring. Inspect lash adjuster bore (prior to installation).
Check cylinder head bolt torque using the following procedure:
Set torque wrench to 45 lb-ft (61 Nm, 40.5 Kg.cm).Check each bolt in sequence as described in the Shop Manual (for Elantra refer to TSB# for proper sequence) to determine if they are at a minimum of 45 lb-ft (61 Nm, 40.5Kg.cm). If any of the bolts are not at the minimum torque, loosen all the bolts and retorque in the proper sequence as described in the shop manual or TSB.

SENSOR OPERATION
Check CAS signal using HDS (see HDS Plot #2 and 3). Conduct visual and "wiggle" test of harness wires and connections to CAS and PCM while monitoring the wave form on HDS.
Accent and Elantra system: monitor HDS to check the acceleration sensor (output voltage at idle is 2.3 V - 2.7 V) while applying sharp blows of the rubber mallet to the left hand (LH) shock tower. Look for sharp spikes in signal.
Using the scan tool, check CTS And intake air temperature sensor (ATS) values when vehicle is cold. Values should be close to ambient temperature.

FUEL SYSTEM
Check fuel injector signal(s) using HDS and/or "Noid Light" (Snap-on part number FID8339). Conduct visual and "wiggle" test of wires and connections while monitoring the wave form on HDS (see HDS Plot #4 And 5).
Clean the injectors (perform after hydraulic lash adjuster replacement).
Check fuel pump/tank/filter for contamination (corrosion, debris, and water in fuel).
Swap injectors from cylinder to cylinder to see if the code follows the injector.

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If only one cylinder has a mis-fire:
Mist spark plug wires and check for arcing.
Remove spark plugs and check for evidence of carbon tracking.
Perform cylinder leakage (leak-down) test.
If leakage is less than 10%, continue to step 4.
If leakage is 10% or greater, remove the head to perform valve job. (See specifics in cylinder head section).
Replace spark plugs. Lightly apply dielectric grease to the spark plug wire tip/boot base.
If misfire is in cylinder #4 (P0304) on Elantra or Tiburon, loosen and retorque the M12 cylinder head bolts to 26 ft-lbs + 60° angle + 60° angle.
In the misfiring cylinder, swap injector with another cylinder.

If mis-fires are paired (ex. P0301 and P0304 OR P0302 and P0303)
Mist spark plug wires and check for arcing.
Remove plugs and check for evidence of carbon tracking.
Perform cylinder leakage (leak-down) test.
If leakage is less than 10%, continue to step 4.
If leakage is 10% or greater, remove the head to perform valve job. (See specifics in cylinder head section).
Replace the coil.

If multiple cylinders have misfire codes, and/or there is a random misfire code
Check LT (Long Term) fuel trim. If over 10%, check fuel pressure.
Check AFS calibration against known good value.
Check for proper operation of EGR and purge control valve.
Mist spark wires and check for arcing.
Remove spark plugs and check for evidence of carbon tracking.
Perform cylinder leakage (leak-down) test.
If leakage is less than 10%, continue to step 7.
If leakage is 10% or greater, remove the head to perform valve job. (See specifics in cylinder head section).
Check fuel sample from the inlet (bottom side) of the filter to check for the presence of water or contamination.
Check intake air supply for evidence of oil in the air cleaner or on the AFS.

If mis-fire code only occurs on cold start-ups
Check oil level and viscosity for evidence of "thick" oil.
Check for after market oil filter (no bypass valve).
Mist spark plug wires and check for arcing.
Remove plugs and inspect for carbon tracking.
Perform cylinder leakage (leak-down) test.
If leakage is less than 10%, continue to step 6.
If leakage is 10% or greater, remove the head to perform valve job. (See specifics in cylinder head section).
Check oil pressure against established standards. Service relief valve, orifice plug, or replace case to correct excessive oil pressure situation.
Replace hydraulic lash adjusters.

I think he his overseas. Find an automotive shop that will let you use an OBD-II reader (also known as a "scan tool" "GTS" and "Malfunction Indicator Light (MIL) Reader").