I have a 1979 510 wagon and just recently I rebuilt the carburetor double checking the assembly of all parts and gaskets and now the cold start is not maintaining the rpms up to keep the engine running. I adjusted the cold start automatic choke at the carburetor and no changes to the problem; the idle adjust screw does no effect to the adjustments, I checked the timing and it is correct right on the dot. I check for leaks around the carburetor as well as the intake but nothing found. Frustration is getting closer to make the decision of buying a new replacement carburetor. Please help.