About 2 months ago I replaced the oxygen sensor in my 1987 560 SEC with a 3 wire Denso universal a month after that the oxygen sensor light in the dash would come on and the engine would get bogged down once in a while, and slowly the frequency of this occurance increased so yesterday I bought a 1 wire Bosch o2 sensor to see if this would resolve the problem, then i took it on a test drive and it was the same if not worse. I am not sure what to do, any help would be great.

Thanks
Josh