I had a problem like this on my pickup. When I replaced my plugs, I didn' replace the wires. The wires were old and when I started moving them around to change the plugs, I must have snapped or broken one of the plug wires inside the rubber coating. So although I couldn't see a break in any of the wires, the plugs weren't getting any juice.

As soon as I put new wires on, it was perfect. Just because the wires aren't showing visible cracks doesn't mean they're fine...how old are yours?

Too close for missiles, I'm switching to guns...

'97 4Runner...SR5, 4cyl (3RZ), 5spd, 4wd, no rust, excellent shape.