Stalls intermittently when driving

For the past month or so, my 850 will randomly stall out on me when driving. It's happened maybe a dozen times and I have yet to be able to find a common thread between these occurrences. Often it will stall within the first few miles, other times it'll run for hours before crapping out. Sometimes it will start right up, or within a matter of minutes, after stalling; more often than not, it takes several hours before starting again (usually after a tow). Sometimes there's a strong smell of gas associated with it, sometimes not.

I've now taken it to several mechanics, none of which have been able to reproduce the problem. However, the suggestions that I've gotten have indicated that it's either fuel related (which I initially suspected) or a faulty sensor. The Fuel Relay Switch and Fuel Pressure Regulator were recently replaced (apparently they were pretty rigged up by whoever owned the car before me). After realizing that this didn't solve the problem, this led the mechanic to then suspect that the fuel pump may be going out, since the way they were rigged would have put an unnecessary strain on the pump. Aside from that, his best guess was possibly a faulty coolant sensor that might be triggering excess fuel to get pumped to the engine, causing it to flood - which would explain why I typically smell gas when this happens.

I've also spent some time reading through the forums and some of the info I found led me to think maybe it's a faulty MAF sensor. After checking the codes, I did get a response of 1-2-1 (MAF); but have also read that that's not always indicative of a problem. I was also informed that my air filter needs replaced soon, but was told that's likely not related.

I don't have the money to just start replacing parts on a whim, not knowing whether or not it even fixed the problem until next time I'm stranded on the side of the road. I'm hoping someone may have experienced a similar issue, or have further insight into what could be going on here.