1996 Oldsmobile Bravada hard starting

When I try to start eng after sitting for a while it wont start unless I shoot starting fluid to it, but after that it will start and runs great as long as I dont let it set long, the fuel pressure with key on is 40, running 40, changed crank sensor, cap and rotor any help would be helpful
I have a second bravada with a diffent problem, starts great but after it gets hot it has no power, check vacum for stop up cat pulls20, changet fuel reg, mass sensor, plugs and wires