hey all , just got a 1995 850 with only 154000 miles , runs ok but sitting at iddle is rough on drive , better on neutral , nice at high speeds, any ideas? previous owner just replaced ignition coil , plugs( not sure what kind) and generic wires so thinking MAF?? wires? plugs? thanks in advance KLaus!!

Is it a turbo or NA? Big difference.

After checking the vacuum lines, be prepared to remove the throttle body and clean it. You might want to spray some TB cleaner into the Idle Air control, slosh it around, and pour out the black stuff!

Your engine has an EGR which can easily clog. The hole into the intake manifold is the size of a pencil, I reemed mine out with a small screwdriver. Getting the EGR valve off is a trick!

For NA engines, clean the PCV valve. For turbo, clean out the PTC nipple.

Turn the key to position II and verify that the check engine light works.
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Keeping it running is better than buying new

Yes, check the codes first.
Running rough?: I'd look at the plugs first, that can reveal a lot,
and check compression while you're at it.
The 95 is the last year that has an OBD code reader, you can read the codes yourself. Do you have the service records? especially the T-belt!
It's probably time for a survey of the motor mounts and suspension.
The EGR system needs checking, stuff like vacuum lines and elbows will
kill you when they rot out, a proactive replacement will avoid all kinds of grief.
What kind of oil is in it? The 850 doesn't like dyno oil, use full synthetic.
Check your tranny fluid and flush if necessary. When you do brakes, flush the system. There's a lot of items need attention, and there's all kinds of videos
and threads to help DIY and save a pile of loot.

Happy motoring, Bill

Is the check engine light on? If not, does the bulb light up when you turn the key initially?

I think the first step is to read the codes (or have a parts place do it for you) and then post back.

Good luck!