problem not solvet

the problem i had with the s-10 4.3 liter 1992 truck is that it will start right up and dies on me. after cranking a bit it will start again but there is vibration and the engine will run rough no misfires it simply drops rpm every once in 10 seconds or so. So after posting the problem here i was told to change the fuel pump relay, don that but with no luck. today the truck simply died on me while driving with low rpm. i parket the car and same deal, crank for 10 or 15 seconds and tha engine comes back to life again is it the feul pump ? i believe there is an electrical problem tothe ignition but can`t seem to pinpoint it. if you people think it is the pump i will replace it but i don`t need to tell you how much work is involved to do. Also, the oil pressure acts funny, while in neutrol the pressure tells you the right story but as soon the rpm goes up the needle hits the roof but comes down again when the rpm settles say around 1000 rpm could the sensor be the problem maker then ? as allways all the help is welcome Dennes