1994 Diamante with the shakes-feels like wanting to stall

I have a 1994 Mitsubishi Diamante that was running good until now...
It started out only after driving for a while that when I got off the freeway at a stop it would kind of shake- it felt as if it was going to stall and the rpms would drop and then pick back up a lil. Now still it does it all the time at a stop and also now when I accelerate???? Also, when this happens the oil light flickers on and off-But I just had the oil changed??It kind of feels like it does not want to go into gear??? Like it wants to stall. What could it be???? Help???? I need my car!!!