Stalling problem
 

I have a 99 Olds 88 that is having issues with stalling. I've replaced the plugs/wires and fuel filter. I had the fuel pump tested and it is at 45psi? It dies when driving and idles funny - revs up to 2 and then back down to 0 (almost stalling out) then back up to 2. If anyone can help, I'd much appreciate it!!!!