Engine surging and bag mpg

[Doubledew]

Hi all, For the past few months I have been getting not so great gas mileage, around 16. Earlier this week the engine started running bad. It idles just fine but from ~2700-4000 RPM it surges and shakes the whole car. This only happens when the engine is under load. It doesn't shake or surge at those RPM if it isn't under load. I have no idea where to start with this so anything would help.

 

[4Running Daily]

I'm thinking you have an injector going out. Go grab some injector cleaner and stick it into your gas tank.

Worth a shot.

 

[fourwd1]

The first thing to do would be to have the CEL codes checked, even if the light isn't on there may be a code stored that may give you a clue.