Retireguy123 knows what he is talking about, precisely what I was going to write. If you are sure that the drain pipe is not partially blocked than the venting has to be the issue. Have you tried Draino or similar product down the drain? Try it, follow instructions, poor down the sink and wait 10-15 minutes and then poor boiling water down the drain, this should unblock the drain if anything is hindering the water flow. Air venting on drain pipes is as important as having clean drains minus the back-up of water of course or even worse sewage. Good luck.
QUOTE=retiredguy123;1805791]It could be a venting problem. Some kitchen sink drains have an "automatic" vent, instead of a vent through the roof. You need to determine which type of vent you have. If it is an automatic vent, it will be a plastic fitting connected to the drain and located under your counter. If so, I would remove it and replace it. If your drain vents through your roof, then you may need a plumber to clear it out from the roof.[/QUOTE]
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