Turbo trouble with JDM supra

[wollis]

I got a 1993 TT JDM Supra RZ. I think I might have a problem with my turbo. When I put the petal to the floor in 3rd gear and the engine hits 4000rpm the second turbo starts to kick in (you can feel the extra boost) but then the power from the turbo seems to disappear. If I keep the petal to the floor the car seems to jump (turbo boost kicks in for a 1/2 second then gos away for 1/2 second then kicks back in for 1/2 second and continues like this untill I lay off the gas a bit). If I do not put the petal to the floor the turbo seems to kick in just fine but then if I put it to the floor at 5-6000rpm the car seems to jump again. In both cases it seems like the car wants to go but as soon as I lay on the gas its like the turbo stops working (or atleast stops working correctly). If I let off the gas a little the turbo kicks back in but certainly doesnt feel like 320hp (I guess 280hp cause its jdm). I was thinking that it might have something to do with the smaller injectors in the jdm models or maybe my second turbo is pouched (I really hope that its not). The car is completely stock except for a turbo timer and has just less than 40,000 original km's. Any help on this issue would be greatly appreciated.

Thanks

Warren