help please asap!!!!!!!!!

ok here we go. i put on a front mount intercooler on my mkIV gti. when i got my diverter valve on, it runs about 7 psi of boost, but it starts stumbling and backfires, causing the silicone boots to blow off and i lose presure. when i run my greddy style rs bov, i push about 1.75 psi of boost, and when i hit the clutch the boost jumps to about 7 psi then down to 0 psi. i have adjusted the waste gate, (stock turbo) and it does no good. i got a 3 inch downpipe and a aftermarket muffler. other than that, no engine mods. i run my intercooler using the stock pipe coming out of the turbo, down throught the passanger side wheel well, to the intercooler, out makes a 180 degree turn then behind the radiator(this is where i put the bov when not using a diverter) and up into the intake manifold. i would really appriciate some help on this before i pull out all my hair.   confused as ***