excorsis, if you want it to act substantively, would have to be excordibus in the abl. pl., since it is 3rd decl. as it stands for the agents of providing counterproductive stupidity it needs to be prefixed by ab. impedire appears to be an infinitive, which would only bear the abstract meaning 'to hinder, encumber'. the sense here is either 'being encumbered' or 'having been encumbered', each of which would have to be rendered by a passive participle agreeing with the subject - 'we'. good old latin, howe'er, has no present passive participle (discluding deponent vbs, which is strictly active anyway), so we are going to have to put the hindrances of the stupid as preceeding our 'pressing on', which is only sensible.
not quite sure what exprimabus is, but i imagine you intend to have the 1st pers. pl. of the verb exprimo, which would be exprimimus. such a verb, however, literally means 'press on to something', i.e. squeeze something so as to wring out or extort something within. one would carry out exprimendum of grapes for wine, par exemple.
press on is really an english idiom, and means little more than 'proceed', perhaps with a sense of urgency. one way of saying this would be
nos, quamvis ab bucconibus praegravati, porro pergimus.
meaning, in literal order: we, though weighed down by so many buffoons, continued onwards.
to use your words:- ab excordibus impediti, followed by a suitable finite verb of advancing.