I have a1998 Grand Caravan 120K with 3.8 motor. At Idle the oil light blinks on. I put a manual oil presure gauge and it has 5-7 psi at idle and 22-25 psi at 3-4 K RPM. The book says it should have 10psi for every 1000 RPM. It could be one of three things. Oil pump, Main and rod bearings,orCam bearing. Has any one had any problem like this or have and sugestions

 

You're probably right about the cause but I'll bet it's a combination of all three.You can use a higher viscosity oil at the next oil change or get a crate engine.a higher volume oil pump would also help but since you would be deep into the engine when you replaced it,you would almost be ahead to rebuild the engine you have.
Here's a link to all the knowledge in the world about lubricants.
http://www.bobistheoilguy.com/

 

oil light blinks and beeps in my 98 grand caravan is the oil pump internal or external? i have tried different oil and changed filter all that is left is oil pump

 

It's internal. Have you replaced the sensor?