1994 Oldsmobile Ciera 6 cyl Front Wheel Drive Automatic 150000 miles

Where to begin? The car stalls out usually right when I start it...Sometimes not. After a while of driving it usually straightens itself out and begins to run normal. But before it straightens out, its a nightmare. The car only eventually runs good by driving it. I cant just let it idle to warm up. Doesn't help. Even sometimes when it is idling normal it will just suddenly stall after a few minutes. I had it hooked up to a diagnostic. He said the egr and cam sensor came up. However, after driving the car around awhile it began to run good, he hooked it back up to the diagnostic and no codes came up at all.

I replaced:
The computer
02 sensor
filter
plugs
wires
cleaned the egr valve

Please help! I have no idea what it can be!!!