If the labda was adjusted, there is a good chance that it was not done correctly which is why you have the hesitation. My car, an 85 had it set to the settings of cars made in 86 and later which had the same result, perhaps in your car something similar happened.
You can check the ingition coil for problems by driving around for a bit, then stop pop the hood and touch the coil, if you can keep your hand on it, it's fine, if it's too hot to hold on to, then it's on its way out. A tip I got from someone
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