I drive a 1997 Altima GXE it's manual transmission about 130,000 miles on it and it's making a noise in the engine when i accelerate and i'm low in the gear, also when i let off the gas and the car slows down (in gear). The sound is a clicking or clanking sound i can feel it in my feet when i drive. I'm just curious if anyone knows what it could be. Thanks.

also my a/c has a "pinhole" leak in it. What would be the cheapest way to locate and repair the leak? thanks

The engine noise could be many things. It is one of those things you would really have to hear yourself to know what it was. As far as the A/C leak. . . You can buy dye to put into the system. It is real easy to see the dye with any kind of UV or black light. You would have have to go from there. Replace or repair the site of the leak.