cause it's junk
A Subaru Forester may stall while accelerating due to several issues, including a malfunctioning fuel pump that fails to deliver adequate fuel to the engine, a clogged fuel filter restricting fuel flow, or issues with the ignition system such as faulty spark plugs or coils. Additionally, problems with the throttle position sensor or mass air flow sensor can disrupt the air-fuel mixture, leading to stalling. Checking for diagnostic trouble codes (DTCs) can help pinpoint the specific cause.
When you stop, you may be letting the clutch out to early.
Several things can cause your car to stall and shake when you stop. Replacing the spark plugs and spark plug wires may cure the problem.
Travelling to slow in a high gear, so clutch in and lower the gear.
Could be a vacuum leak
The engine isn't receiving the correct amount of fuel which will stall the motor. Also if the oxygen censor isn't working properly then the motor will stall.
probs a mechanical problem
Does it shake and stall when decellerating or at anytime? because mine seems to do that but its only when decellerating at a stop light or stop sign or whever and it dont always do it.. only after long drives. (1992 Pontiac Sunbird). It might be a bad EGR Valve.
CHECK COIL PACKS
is the exhaust pipe pluged causing back pressure ?
don't have an absolute answer, but mine started doing that last summer. Most often it would shake and shudder and worry me that it would stall out. But never got that bad. Then after 7 months of that, noticed some steam coming out the front end. Not sure the answer on that either. The dealership noticed right off the coolant was way past due for replacement. They changed the coolant, no more steam so far and the shudder/shake has been a very rare occurance now.
could be that the choke is not adjusted right