Pinch test: pinch off the fuel. See how long it takes until the idle speeds up then dies. About four seconds until it speeds up is a good starting point. This is only meant to get you in the ball park.

Does it die when you increase the throttle slowly?
Or only when you do it quickly.

If it happens when you do it slowly, your main needle could be too lean, and your idle setting is compensating for this. If the main is set according to the book, then maybe there is a blockage somewhere.

The usual procedure is to get the main needle setting right at high speed, then adjust the idle. The pinch test is a good place to start, then adjust for good transition without being so lean it pops and crackles when you run through the lower speed range. At any speed, pinching the fuel line should result in a slight speed up before it dies.