I have a 91 DX with a 90 LS swap, and I've been getting a seemingly random code 43 - fuel supply system. What causes this? It used to only do it while cruising on the highway, and I could always just turn the car off and back on and it would be gone, but it's been doing it more and more, and now it has started doing it just tooling around town. Nothing really seems to be affected when it happens, it's just annoying for one thing, and also there's obviously something wrong to make it throw a code. but where should I look for the problem?