My 1994 E320 Cabriolet with the 104 straight six has a misfire when I accelerate or the engine is under load.

Problem began late last summer at 102,000 miles when I had a missfire periodically while at idle (i.e. at a stop light). I figured it was one plug, so I replaced them all. Ran great thru November, then I garaged the car for the winter. I started using it again last week and the very same misfire started happening. Runs okay at idle, and if I accelerate slowly I'm okay. But if I press down a bit harder, the engine stumbles and I've even heard an internal backfire once or twice. Since the plugs are new and properly gapped and torqued (I pulled them and rechecked) I'm mystified.

Other posts indicate I could need either new spark plug wires or a harness. I've checked them and they look good although I'm sure a replacement wouldn't hurt. But I hate to do that if it doesn't solve the problem. Any recommendations or suggestions for me?

Thanks!

Allways change the 3 coil /plug connectors when changing plugs on a 104... along with F8DC4's ONLY.