1988 300sel Fuel Distributor Problems

This is my very first mesage here and would appreciate some help. I recently purchased a used 1988 300 sel MB 179,000miles that was running well until a mechanic decided to give it a tune up. All hell broke loose from there. I have ploughed in about $3000 thus far, trying to fix this old battle horse. My wife is not too happy about it. The problem is that it does not start when the temp gets cold and when it starts, it hesitates when I step on the gas pedal. Sometimes I feel like it need a " choke" or something to help the fuel delivery. I have changed the battery, fuel filter, fuel pump, fuel relay, bought a used fuel distributor (which we suspect is the main culprit), changed the plugs, trans mount, flex disc and idle arm. It is a beauty to drive when it starts but at times when it doesn't I have to repeatedly start or wait for a while before it kicks in. I need help before I consider purchasing a new fuel distributor which is rather pricy. Where can I get a refurbished fuel distributor? Best Regards.......EKOWBEE