'91 9000T stalls at speed

My 1991 2.3 9000T stalls at speed or when I try to accelerate going down the road or from a stoplight. After it stalls, restarting is very difficult, often taking about 5 minutes of cranking attempts. After it restarts, the engine will then run for awhile and sometimes stumble and stall again. The problem doesn't seem as severe while the engine is cold.
So far I have replaced the spark plugs and the DI cassette and checked the lines to the APC valve to make sure they are still intact (connected and without cracks). I also noticed that the APC gage no longer moves out of the green zone.
Any suggestions on specific items to check or where to look are appreciated.
Walt Kienzle 1991 9000T

is the check engine light on?
you might want to look at your fuel system it could be the fuel filter
but i'm just guessing here

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No "Check Engine" light other than the normal illumination during startup and after it stalls. I'll keep the fuel filter in mind. Thank you for the suggestions.
Walt

Salutations:
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I think es may have it right - but have whoever turns your wrenches check that the pump the regulator are still within spec.
What is odd is that it operates better from cold - which might indicate a really oddball heat related problem with a timing sensor on the block if that model is so equiped - which I'm not sure it is - so back to fuel system etc.
Mind kicking back what it does turn out to be when you get it nailed?

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Right now it looks like the problem is a malfunctioning LH Jetronic 2.4.2 unit. http://www.thesaabsite.com/900old/c900Hybrid-circuit-failures.htm seems to describe the symptoms I experience quite accurately. I guess I didn't let the engine warm up sufficiently after the power loss and stalling to notice the improvement after it was fully warmed up. The part number for my car is 88 57 187 and doesn't seem to be available from my usual sources in the US. Sourcing suggestions (other than e-bay) are appreciated.
Walt Kienzle 1991 9000T

Salutations:
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<snipped as being completely off the mark - sorry>
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Well that is weird I have to admit. As to finding one, your best bet might be to give Jak Stoll(?) a ring and see if he has any uprated units. I mention this because I'll wager an uprated unit will come in not a lot more dear than certified working unit.
Thx for kicking it back in, Merry Christmas brother Walt.

Walt Kienzle wrote:
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In another ( non-Saab ) vehicle I had a problem that prolonged long runs at speed would result eventually in a loss of power. After which the engine would run erratically then often recover.
It went away when the fuel filter was replaced.
Graham

Pooh Bear wrote:
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It could also be the fuel cut-off mechanism that is not properly recovering after cut-off. And the cut-off might again be triggered ny other things e.g. a sticking wastegate.

Buy a spark tester and carry it with you, so when it happens again at least you can narrow the problem down.

Misterbeets wrote:
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And how would you use one of those on this car?

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...presumably once the engine is running it's firing normally on all 4 pots, so *possibly* more likely to be fuel rather than ignition as suggested by others. May be worth checking all electrical cnx associated with fuel system - I once had a VW Passat that had similar symptoms and defied VW agents for months. Eventually out of desperation I broke/cleaned/remade every multi-plug I could see around the fuel system and this 'fixed' it. This sort of problem can apparently also be caused if you have the incorrect fuel filler cap too, as an unvented cap can cause a vacuum in the tank (though I reckon occurrences of this are mighty rare). Good luck!

Good FAQ at http://www.thesaabsite.com/9000/9000faqs.htm#when