89corolla ?s

ok my car 89sr5 has lil engine prob like when some time s im driven n i slow down or stop my car sound like it wana cut off n my oil lite come
i think i dont have enuff oil pressure but it only does it in gear no park wats da prob n wat can fix it?

also wat mods can i do 2 it performance wise n wats da bigest size rim i can put on wit out fuckin it up?