hey im new here purchased a 97 altima se a couple weeks ago. the engine vibrated when idle or going about 10-20 mph. no heat and when stopping at a light the rpm would be between 1000-2000. when it comes to cars i know so much so i changed the thermostat, radiator ( radiator is clogged and disgusting) and water pump. idle wasnt so rough had heat and car stopped over heating. until this morning i was driving to work and my check engine light is on. now when at a light rpm is between 500-1000 is that normal? i know i sound stupid lol but i am new to owning a nissan and idk what to hear for and so forth.....thanks