It shouldn't be very stiff. I had trouble of one sort or another with every component of my 87, though. So, first check the cable for rust, fraying and binding. Then check the pivot on the pedal itself and lube that. Then get under the hood and check the pivot on the bell crank that operates the linkage to the throttle body and lube that, also checking for wear that might cause it to hang up. Then, finally, lube the throttle plate pivots on the throttle body.
As an afterthought, make sure too that the transmission cable isn't stiff. Try disconnecting that (not while running) and see what difference that makes.
It shouldn't be unusually stiff, so I think unless you're used to something very soft indeed, there's something wrong.