I have problems with my sons 96 Formula surging mainly at the top of 2nd gear, around 85-90 mph with the 2:73's. I installed a walbro 255 and a napa FPR back in May, about 5k miles ago. I put a fuel psi gauge on it today. At idle it holds about 35#, pull the vacuum hose of the FPR and it goes to 45#. Pressure drops as soon as you turn it off so naturally its hard to start. Injecters are not leaking and I replaced the fairly new fuel filter today. No noticable fuel in the FPR vacuum line.

I drove it with the gauge hooked up and sure enough its loosing pressure by the top of 2nd gear. It will go from around 35# up to around 42# when you go WOT. But it drops to 33 to 35 by the top of 2nd gear.

I read another thread where a guy had a simular problem but he was running an after market FPR. Went back to the stock FPR and cured the problem.

Does this sound like a FPR problem or fuel pump?

 

It seems fairly common to have problems with the check valve in the Walbro pump. That would account for the loss of pressure, if you have ruled out leaks, leaking injectors or a faulty fuel pressure regulator. It also possible you don't have the hoses on tight back in the tank.