Rough idle, rpms move slightly only when lower oil readings?

(2011-04-06 14:20:35)

1. sniperlif3 Says: I have a 1993 gmc sierra that has a chevy 350 small block and an automatic transmission. Generally when my truck is cold i get about 70 psi of oil pressure and sometimes when the truck is fully warmed up or has been driven for a while. The psi drops to 40 psi at idle and will jump to 60 psi when the rpms get to about 1000+rpms.
When my psi is at 40 and i am idle at a stop, i get a rough idle. The rough idle sometimes makes the rpms jump around about 30 higher and lower from the base reading of about 500 everytime that i feel the rough idle.
If i keep the rpms below 1000 and just keep it there while driving (such as when just moving slowly in traffic) the truck feels like it is having trouble keeping the rpms constant and i can hear a noticable change in the engine speed as if it could die if it was worse.
From a stop, if i accelerate while staying under the 1000 rpms there is also a delay that feels as if the timing was off.
I checked and set the timing myself back to what factory specs, and manual both say. It is a new distributor, cap, rotor, coil, ignition switch, idle air control, fairly new plugs and wires, new camshaft and lifters, cleaned the Throttle body,. And i experience this before and after i installed these parts.