FTM Clone Oscillation with 1 amp

[Stratomaster]

Hello,

I built an FTM clone that I've been slowly perfecting over the last few years (thanks to you all so much for all your help).  However, I noticed that with one particular guitar (Strat) on one particular pickup (bridge) with one particular amp (Deluxe Reverb RI) the pedal will squeal into feedback at any volume remotely approaching stage volume.  It is not the case with my other strat or any other guitar or on any other amp.  I have used shielded cable to and from the circuit board and have tried to run the input and output far from each other.  Is there anything else I should try?

In case it helps, it doesn't really matter what setting I have the "Fuzz" knob set to, and my volume is slightly boosted from my clean sound.  Tone is set low because it gets real harsh real fast.  Thanks in advance for your input.

[Stratomaster]

No bites?  How about if I make it general?  How would you stop a high gain pedal from oscillating?