Mitsubishi Repair: 2000 mirage 1.8 , P0300 random misfire, fuel injector problems, crank sensor

Question
hi and thanks in advance

i too am a mechanic (diesel-hd-transit bus) and also A.S.E. cert. but still cant figure out my problem : /  

2000 mits mirage 1.8 p0300 random misfire %26 it never calls for any paticular cly

very random , cold, hot , once a week to once a drive . it would stumble all of a sudden (feels and sounds[coming from the exhaust] like i just lost a cly or a coil pack [it has 2 coil packs] , feels like losing all of your timing advance . but when  i let go of the gas pedel for a sec and get back on it , it runs ok again ....

i have changed and done ,

timing belt
cam sensor
crank sensor
both coil packs
wires and plugs
fuel filter
air filter
oil and oil filter
pcv valve

and it still continues to have the misfire : /

up until this problem the car has been super and trouble free
only needing regular service , btw all parts used are from the mitsubishi dealer and even speaking to their mechanics they too are stumped by this .short of using their scanner this is how far i have gone with this.                        

                       thanks again for your time  

Answer
Daniel,
Check for low compression.  It's possible there's a crack in the head and the lack of compression causes a misfire.  Also check to make sure the fuel injectors are firing.  Because your misfires are so random, this is difficult to examine and your computer doesn't seem to be recording any fuel injector problems.  I would also recommend checking your ECU.  If there is a problem with the ECU itself, it can cause random problems like the ones you're experiencing.
Good luck!