Idles great but misses badly when accelerating

95 GMC Sierra, 140,000 miles, 2wd, auto, 5.0 V8. Replaced dist cap, rotor, plugs. Idles great but misses bad trying to accelerate or go up hills. I didn’t replace the wires. Could bad wires cause this? Needed tune up and idle is much better now but it ran better after warming up before. I checked and did not damage any vacuum lines.

Yes could be secondary ignition wire related.If you have the time get a spray bottle filled with water,at night spray areas around the wires,look for arcing,or you could just replace 140,000, they are probably due,don’t get your hopes to high.

Any OBD1 codes? Thinking fuel pressure,filter,pump.

Had this happen on a similar vehicle…The fuel pump is connected to the tank fitting with a short piece of rubber hose. This hose had split open, spraying fuel, dropping the pressure to almost nothing…Check fuel pressure before you drop the tank…

Are the wires on it now the original ones? If not, how old are they? I’d try that first. Rocketman