1988 bmw 3.5 engine won't start and backfires through intake

150K on a clean looking car. The car ran okay a few days ago with minor exhaust leak, and it had a nasty power steering pump leak that the guy I got the car from just kept adding fluid, but now it cranks but won't start. I did get a backfire while cracking, it blew past the rubber intake hose attached to throttle body...Any leads where to start. It sounds like it on the verge of starting.

Thanks to all who can help.

1988 bmw 3.5 engine won't start and backfires through intake