Hello all. I am a typical woman who don't know crap about vehicles. My 2004 GMC Sierra has decided to start messing up on me. sometimes when I go to start the truck in the message display it says "reduced engine power" it won't do anything when i press the accelerator and it idle's high I have to turn the truck off and re-start it over and over again before it decides it wants to run right. I live in a very small town and don't know many people around here to ask for help and cant find that thing you need to check "code's" I hate being the typical woman and having to get on here to ask but don't know what else to do since i don't have a code checker. I have asked other people and the answers I got just don't make since to me the answers I have gotten are transmission to me doesn't make since I would think one has nothing to do with the other, fuel filter which i have had to replace a clogged fuel filter on a different vehicle and this truck isn't running like that. And someone told me it could be possible I need an oil change which makes since but then my question would be how come it didn't do it before. I read the owners manual and it said that it only goes in this mode when it over heats and that is definitely not the case because the truck is cold when it does this. Please all suggestions will be appreciated. I am still working on getting the codes pulled just don't want to sit back and do nothing while I wait because it is getting aggravating. Thank you so much in advance.