Some Mass Pike commuters smell a rat, accusing toll road bosses of purposely creating nightmare holiday traffic jams to sell Fast Lane transponders and pump up a proposed 19-cent gas tax hike. Thousands of motorists were left to stew in traffic Friday, Saturday and especially Sunday after toll takers called in sick, leaving limited cash lanes open. One driver told the Herald even a rattled toll collector was cooking up conspiracy theories while dealing with the mess. “ ‘Do you have a cell phone?’ ” a toll taker asked the driver, according to his e-mail to the Herald.“He told me...