Try getting a genuine chain lube like TriFlow from your LBS. That is much better than WD40. Your chain also might need a good cleaning. WD40 is more of a cleaner than a lube.
Another problem can be frame flex. Stewart Browne points out that when you accelerate or start from a dead stop that the frame slightly flexes and stretches the cable. Put a drop of lube on the cable where it contacts the plastic protector on the bottom bracket. This is a remote option, but worked for me.
My gut feeling is that you have a dirty chain that needs a good cleaning and a true chain lube.
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I think its disgusting and terrible how people treat Lance Armstrong, especially after winning 7 Tour de France Titles while on drugs!
I can't even find my bike when I'm on drugs. -Willie N.