Going to try once again.. ;)

Now I've noticed another problem with my GLT Brick and I think I know what might be the cause of it. I've noticed that as the car heats up and runs for awhile (Hour or so) While driving it around town while comming to a stop the Oil pressure will drop down (causing the oil light to come on) and the car will sputter and die. While it is cold it runs great, and it even runs great while it is warm (for awhile). I thought maybe it was time for an oil change as it seems every 2500-3000mi the oil breaks down and oil pressure gets continually worse. And then another thing came to mind. While my father owned the car he lived up in central California, the tempatures there are usually between 40-80f. Now where the car is now (Central Arizona) the tempatures are normally 70-120f (It's been 100f+ every day for the last few weeks.)

Right now the car uses 15w-50 (Moble1 Synthetic). Should I use something thicker maybe?

One more thing as well, perhaps this isn't oil pressure related at all.. someone else suggested that because the car is hard to start cold (You have to crank it even after the engine fires, which causes mis-fires and is bad for the starter i'm sure..). That the fuel pre-pump in the tank could be bad? Might that be it?

Anyways, thanks much in advance.

One last thing to mention, while accelerating from a dead stop while cold, when shifting between gears the car will stumble if you let the clutch out right away (And sometimes even grind to a halt.). Might be helpful for someone to know if they are trying to help.. ;)

Thomas