When the engine is cold i have great oil pressure, and when the engine is warm it has great oil pressure at idle, but when i put it under load (pedle to the floor) at lower rpm, or driving it normal down the highway the naling it the pressure will slowly or suddenly drop??? Plez ive been fighting this for a while and do not have a clue what it is, Ive tried everything!!!!

 

Also i forgot to mention, this is on my 86 chevy truck, 350 rebuilt engine.

 

My car did this to me this weekend. it would have normal oil pressure until i gave it some gas and the oil pressure would drop. Mine turned out to be a little low on oil. It could be that or a clogged pickup.