Misfires and GT1 issues

[TrickerZ]

I've been having misfires on my 2000 X5 and finally decided to get a diagnostic head to figure out what was going on. I have the OBD2 head (BMW USB OBD Diagnostic Cable Inpa Ediabas NCS Expert Dis V57 SSS V32 Progman GT1 | eBay and was able to pull the codes and found that all cylinders are misfiring. I'm guessing it's either a vacuum leak or a fuel pressure issue. I don't drive the car much, and it seems like it takes awhile after I start driving it again before it starts to misfire and shut down cylinders. Subsequent restarts reveal misfires soon after it reaches idle. If a fuel pump is going, would it act like that? What's the best way to find a vacuum leak? Starter fluid?

Secondly, I'm guessing I need the round diagnostic head to really use DIS. Can I use one of those OBD2 to round adapters, or do I need a special head for DIS? I also need to remove my suspension from the sequence and would like to know if I need a ZCS code if I use DIS v44.