Engine misfiring with P0300 code

[kashmir]

I know a lot has been said about this issue...i have had this problem with my 2005 4.4 ever since I owned it. it has 75k miles on it.BMW has worked on it 4 times and performed all major repairs including intermediate levers. I believe BMW spent at least $15k under warranty. Last repair was done in 02/11. Last winter , I had one minor misfiring issue. check engine light didnt turn on. so I ignored it. Two weeks ago, i had engine misfiring episode again on a cold morning. engine light turned on. It has been running fine since then though. This morning I took it to autozone--error code was p0300--which, as most of you already know, means random engine misfire.

I dont want to spend thousands on repairs when it seems repairs dont work. What would be the best thing to do at this point. should I take it to dealership and have them check the codes in detail and possibly do they repairs if it points to any minor issue? Do they sell any code scanners that can give me detailed errors codes like a BMW scanner would do?

Alternatively, should I just gets the check engine light removed and forget about the issue. I noticed in a related post someone had done that with a bluetooth code reader. I have an aftermarket avic- z100 in the truck now. would this tool work with my x5. I am hoping it has nothing to do with radio bluetooth.

thanks very much in anticipation.