trying to figure out y my mpg are so bad... when i got the blazer 2 years ago it was decent..expensive to fill...yet decent and it made the gas last..now a days it is just sucking gas and i almost havnt gone anywhere...and the power went down the drain with it..could someone help me out here...idk what is going on..

 

First thing I would do is a full tune up and oil change. It could be a lot of things but dont jump to conclusions right away. any other symptoms or engine noises? how many miles on it, older exhaust? Take your time with an open mind, you`ll figure it out

 

Have your driving habits changed at all? What is the exact mpg's you're getting and were getting?

 

If everything on the engine is in tune I would suspect a clogged converter

 

+1 on the clogged converter. You can either take it to an exhaust shop and have them do a back pressure test, or do some DIY tests. They include, smacking it to see if it rattles, getting it up to operating temp at night to see if it glows and removing an upstream o2 sensor. When you remove the sensor it will be loud and you shouldn't drive very far, just enough to see if it helps by removing some back pressure. You will also get a CEL until you put the sensor back in.

 

as you can see we need more info to be of much help. but that being said ... lets start with the basics. do you have the right AC DELCO plugs in it? any other brand, even the ones listed for the truck WILL cause problems!! it sounds stupid but i have had it happen to me and some friends with autolite, bosch, ngk and others. next check fuel pressure, too much or to little will effect drivablity. chech the timing, is it correct? any mil codes? let us know.