P0301 and Stumble: 98 ZX2

The stumble occurs at idle once the engine has reached temperature, and at about 2,000 RPM on acceleration. The P0301 code comes up.

I’ve changed the plugs. The plugs were worn (300,000 km on them) but all four looked in good shape. It ran like a top for a week then the problem came back.

The vacuum seems fine at 19-20 in.

I also swapped the 1 and 2 injectors and the misfire stayed on 1.

Does anyone have any other ideas to narrow it down?

I appreciate any help.

Tim

Did you gap the plugs when you put them in? Did you check the resistance on the wireset? Compresson check? A burnt valve also will cause this code. Otherwise the only thing I can think of is the coil pack. Good luck