noise with jfet

[Joaquín V]

I am trying to make an overdrive with two JFETs. Everything is fine until I try to put a 10uf capacitor on the source of the second fet to get more gain. When I put it in and turn up the volume with the gain at maximum, I get a very high pitched sound constantly as if it was feedback, even if it is bypassed the noise appears. Any clue why it happens?
thanks

 

[temol]

Is it breadboard, stripboard, regular pcb? Potentiometers on wires? Is it first stage with the 10u cap? How about making it three stage circuit with less gain in each stage? Can you post a schematic?