I'd see what codes are being thrown. Mine misfires on cold startups but not consistently. It's likely the intermediate levers. A restart or two is sometimes required, but pales in comparison to replacing the levers. There is a software fix to try if the levers aren't too worn that moves them from 0.3mm to 0.8mm, but fuel mileage and throttle response suffer. Get a shop that knows these engines. Throwing that kind of money at it to not solve the problem is useless. I'd stop spending money with these guys and get an independent that knows the cars and engines very well. If they know what intermediate levers are, are aware of the recall campaigns and have perhaps done a few valve seal jobs, you're at least working with someone that knows their arse from a hole in the ground.

There is a thread on here that has some recommended shops across US and Canada.

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Daily Drivers:
- 2008 535i, 320,000km
- 2004 X5 4.4, 01/2004 production, 420,000km
- 1997 328i, 350,000km

Track:
- 1996 328i, track/race car, ~300,000km

Winter:
- 2013 Ski-Doo MXZ X 800 E-TEC, trail can
- 2007 Ski-Doo MXZ Blizzard 800 HO
- 2001 Ski-Doo MXZ 600 w/800 engine, exhaust
- 1978 Ski-Doo Olympique 340 (vintage race sled)
- 1977 Ski-Doo Olympique 340E