I have my Cleveland engine running now quite nicely. There is only one thing left which is engine jerking at low speed. The engine starts to jerk when I'm in dense traffic and just want to roll in engine idle in first or second gear . A light push on the accelerator pedal and jerking goes away (...but car accelerates, too). Jerking is only below 1,800 rpm. I have already played with ignition timing , idle mixture screw setting, different types of spark plugs, various carburetors and all that had no influence on the jerking. My theory is that jerking is linked to the valve overlap of the installed aftermarket camshaft. I found that at engine idle with 900rpm I have only 10inHg of total vacuum. Is it possible that during idling there is quite some of the exhaust gases entering back into the cylinders via the exhaust valves resulting in a sub-optimal combustion. Does that make any sense? I forgot to mention that the engine was completely overhauled (no issue with compression or valve leakages). Many thanks for any idea, thoughts or your shared experiences.