I have a 96 Chevy with vortec 5.7 had it built now it a 383 stroker now it runs for a lik bit the itbwill die at 2800 rpm and shows a po341 and a po339 cam and crank codes I need help on why this hap

P0341= Camshaft Position (CMP) Sensor Performance. The number one cause of P0341 has been that the distributor was removed and installed... but not synchronized correctly. Yours rebuilt Correct? It was removed. You'll need to synchronize the timing marks on the distributor and the crankshaft pulley/ timing cover. You'll need to use a repair manual (or a Google Search) to find out how to install the distributor correctly. Otherwise if its bad Read copy & paste url: http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test-the-cam-sensor-2

https://www.engine-codes.com/P0339.html

P0339: Check the wiring to the sensor - could be a pinched, corroded or shorted wire or connector. Also don't rule out the new sensor ... anything is possible.

I think you need to use a multimeter on each crank sensor wire as it likely has a break in it, may have to disconnect the battery while testing them and check for open circuits and move the wires around to see if values change or stay the same, look on net/youtube for directions for checking for shorts with a multimeter.