My car 190E 2.6 has developed a rough idle and I have narrowed it down to a fuel problem. To be precise, a fuel problem at cylinder #1. I let the car idle at operating temp and starting from cylinder #6 I pulled the plug wires one by one. Each time a pulled a plug wire, the car idling would get much worse until I put it back. Finally got to cylinder one and pulled the wire and noticed no change at all, however there was definite spark at the wire. I moved the plug from cylinder #1 to cylinder #2 and the problem was still at cylinder #1. I then disconnected the fuel line from the injector and put the end into a bottle and cranked the engine and I got maybe a less than an ounce of fuel that dribbled into the bottle. I pulled the entire line off to check for blockage and it's clear. I'm wondering if a faulty fuel distributor would only affect the one cylinder or if a fuel pump failing would cause this. I last replaced the fuel pumps in 2016 with Walbro pumps. Other than the rough idle the car runs fine. Thoughts, suggestions, or advice is much appreciated.

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1990 190E 3.0L