Are there any cases where a defendant has successfully argued that counsel misfeasance during the plea process contributed to her pleading guilty to a charge of attempted murder?

The associated claims of ineffective assistance of counsel are not related simply because they both deal with counsel's behavior during the plea proceedings. See United States v. Ciampi, 419 F.3d 20, 24 (1st Cir. 2005) ("[A] petitioner does not satisfy the Rule 15 'relation back' standard merely by raising some type of ineffective assistance in the original petition, and then amending the petition to assert another ineffective assistance claim based upon an entirely distinct type of attorney misfeasance."); Schneider v. McDaniel, 674 F.3d 1144, 1151-53 (9th Cir. 2012) (ineffectiveness for failure to obtain competency evaluation to stand trial not the same as ineffectiveness for failure to develop a voluntary intoxication defense). Those ineffective assistance of counsel claims are supported, in large part, by the same core of facts underlying petitioner's other claims - her competence during the plea negotiations in the original petition and the factual basis for the attempted murder charge, based on petitioner's mental state at the time of the crimes, in the amended petition.