I use the front tank, it pumps to the rear tank?

My truck has two tanks and when I run the front tank or the rear tank, the fuel is pumped back and forth, from one tank to the other. On the rear tank, the truck runs fine, beside pumping from one tank to other tank. But when I use the front tank, it pumps to the rear tank for a short while then after about 5-10 minutes, the truck starts too buck, chock, fart, until I switch the tanks, if I'm driving the check engine light on the dash comes on, once I switch the tank to the rear one after about 2-3 minutes the light will go out. The light only comes on when I use the front tank and it only bucks up when I use the front tank.I have changed the fuel sensor check valve and the fuel line gas filter, now it runs for a while normally then starts to buck, on the rear tank, no problem other then the pumping of fuel to the front tank. This was a recall problem for Ford in 1992, but they will not honour the recall because of the age, and the cross over fuel switch which is on the frame rail, is no longer available from ford, could that be my problem and is their a after market part I can get from somewhere. Thanks Robert