Bought a 98 forester, thought it was a deal, fixed gas lines, new brakes, cleared check engine light came on with misfire codes in all four cylinders. Car idles fine drives ok once accelerated. During acceleration and deceleration the car spits sputters and stalls. Gave car full tune up and now misfire coded in cylinders 2 and 4. l do not know what to do...any suggestions? Please?

So your getting a misfire. lets see..either your not getting air in the cylinder (unlikey), your not getting gas (full pump or injector problem) or your not getting spark (ignition/spark plugs).

My guess is your timing is off.

l would tend to agree with the timing issue.
It is more than likely not air or fuel unless you have a poor O2 sensor. l would get the timing belt checked. You said you got a tune full tune up, but my question is when they conducted the tune up the codes should have been addressed. Who did the work and how much did they actually do? Also check your spark plug wires you could have a bad wire and getting a low spark. It is a number of things.