a couple questions-- how can i fix this w/o going to a person to see if there's even a major problem-- if its like a leak or something i wanna fix it myself.- oil's fine, gas in car, belt squeeks but i've had that problem b4 and the engine light didn't come on (that was in a 98)

also my car rumbles @ a stop when it is in drive it feels like its gonna shift gears or something its very shakey could this be a leak someone else was talking about? what else could it be?