Is running an engine at a real real low rpm that bad? I have to basically "4 wheel" my Corolla into some spots to go fishing. Today, the road I take was in real bad shape, so I had to go real slow up a rocky/rutted incline and I **** near stalled (manual transmission). I was at about 400-500 rpm for a brief moment untill I got over the hill. My car doesn't knock like some engines I've heard when lugged real low. Is this harmfull in the long-run?