i'm havin problems w/oil press. on 2000 4.3 silverado,the display reads low oil press.& change oil.i replaced timin gears& chain,cover,r&r oil pan gasket,primed oil filter,filled w/ oil.started the truck& it ran but had oil prob. display.p/o r&r intake man.gaskets.i removed dis.rotated oil pump w/ screwdriver& seemed to operate smoothly.the dis. does'nt seem to be engageing oil pump cause there's no evidence oil inside valve train after it started.could intake man. install cause misalignment of dis. shaft to oil pump or should i be lookin for somethin else? the truck had set @ p/o for 6 mo. b4 i got it started. any advice & or suggestions is muchly appreciated!