I purchased a 1979 Coupe deVille with the optional fuel-injected 425. I bought the car, non-running, because it had Dayton knock-off wire wheels on it, easily worth more than the whole car. After my shop replaced both fuel pumps and performed a tune up (wires, cap, plugs, all filters, etc.), it fired right up, but turns off after a couple of miles of driving, when warm. Restarts when cold again. My shop knows nothing about the first year Cadillac fuel injection, but I suspect the fuel pump relay or timer, if there is one in the system. OEM fuel pumps were the same as used on early Volvos and BMWs. Anyone an expert on this f.i. system? My ultimate goal is to pass CA smog, so I have to get it running perfectly. With the new exhaust, radiator, heater core, and upcoming leather interior, paint, and tires, I've too much invested to stop now!