mullet11223

i have a 85 volvo 740 gle. when i start speeding up it starts loosing power. when i get on down the road it clears up and runs fine untill 5 to 10 minutes later then it does it again. I have put new plugs,wires,fuel filter,air filter and fuel pump relay. Could it be the fuel pressure reg. It acts like it is eather loading up on gas or not getting enought. Please help.