I have a 93 chevy blazer 4.3 vortex im having problems with my idol jumping high in park then as i put truck in drive it shouts off what can cause this to happend...

Have you tried a throttle body cleaning?

I tryed many things im having more of electral problems im thing i just had tranmission rebuilded and ever since the rebuild i been having my idol jump up n down and runs at high rpms i replaced the throttle position sensor but it didnt help my fuel pump went out so i put a new one my blazer is all digtal as well whn i hit the gas my lights dome out alil so im not to sure what can be the problem

I havnt checked inside the spider yet maybe thats acting up?