P0601 GMC -

Question

Hello, is there a charge for this.  I took my 2006 to dealership today. check engine light has been coming on then go off, etc. car has stalled and local place ran a check and said it was a ecm failure and need to replace, take to dealership I did.  They ran a computer check and could not get a reading, check engine light was on. Said need to replace ecm unit, then hook up again and see if check engine light goes away, or reads another code.  Does this sound correct.  Also said the throttle needed to be cleaned/  My son said to wait on throttlr thing as this is reg. maintenance and replace the ecm unit, so it can read codes that car is throwing. When i took it to regular guy frist he said needed to go to dealership as codes p601 and p430 and p304 and p1205 and p1206 came on. said it was really the ecm and ti take to dealership, where it is now to replace ecm unit.  I am a senior and just upset and confused. iis this correct