Clogged Fuel rail or injectors?

5 years is probably alcohol added fuel, as such it likely absorbed water from the air as well as the additives in the fuel leaving deposits in the system. That car uses a return style fuel system so I would suggest disconnecting the return line from the rail and run a hose from that into a gas can or two and go to the electrical center under the hood, find the red wire that is taped in the harness and is the pump prime feed. Hook that to battery positive and pump out a quart or two into a glass jar. Now let it set on the counter and see what settles out, water will settle to the bottom. If you want to do the full test you use a metric graduated cylinder Usually 50 ml. Now you put in 10 ml of the gas and 2 ml of clean water. Shake that up and then let it set for 15 minutes. Now look at where the water separates from the fuel. You added 2 ml. So if that is where it still is, you have no ethanol and no extra water. Now say you have instead a separation line at 4ml. Well you know you added 2, so you subtract 2 and then multiple what's left by 10 and get the percentage of alcohol/water in the fuel. So 20% if the normal fuels are 10% you know you have a real problem. At that point I would pump out as much as possible, then replace the inline filter and then add some clean new fuel and some B12 Chemtool. Then let it run. That should the crud out of the system. From there it's just the regular things like looking over the wiring for rodent damage and cleaning the electrical system connections.

You're welcome. Let us know how it turns out.

Good to hear. Yeah rust is an issue that is worse with ethanol as it acts like a cleaning solvent and removes pretty much any film that the gas itself might leave behind so the steel rusts faster.

Great news. The Roadmaster was a good car for it's time, the 3.8 is one of the better GM engines as well.