As of late, my 93 auto (just turned 100,000) has been vibrating when I start it or step on the gas in park or neutral. I can feel the vibration through the steering wheel. It also makes a throatier sound than normal, especially at 2,000 RPM while in neutral, seems to quiet down a little at RPMs above 2,000 (there are no mods to it). I checked all the vital fluids and routinely inspected hoses, belts, etc. Performance doesn't seem to have suffered. It's really hard to explain, but it hasn't happened before and it doesn't seem normal. I have owned this beauty for 7.5 years. I'm just waiting for the factory original head gaskets to blow. Any ideas?