# Gas Mileage **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [June 25, 2009, 4:17pm UTC](https://community.cartalk.com/t/gas-mileage/32375 "2009-06-25T16:17:41Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![bobm58](https://avatars.discourse-cdn.com/v4/letter/b/c68b51/32.png) [@bobm58](https://community.cartalk.com/u/bobm58)\ **Post date:** [June 25, 2009, 4:17pm UTC](https://community.cartalk.com/t/gas-mileage/32375/1 "2009-06-25T16:17:41Z")
I have a 1991 Dodge Dakota 4X4 extended cab with a V6 3.9L engine with 141,000 miles. A few weeks ago it began to idle rough and would often kill coming up to a stop sign. This lasted about 3 days and then it started running fine again, but ever since then my gas mileage has gone from 16-17 MPG to 12-13 MPG. I have changed the spark plugs with no effect. Any ideas? ---
**Author:** ![Roadrunner](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@Roadrunner](https://community.cartalk.com/u/Roadrunner)\ **Post date:** [June 25, 2009, 5:51pm UTC](https://community.cartalk.com/t/gas-mileage/32375/2 "2009-06-25T17:51:05Z")
Check and clean the throttle body and IAC valve. You MAY also have a clogged fuel filter. ---
**Author:** ![bobm58](https://avatars.discourse-cdn.com/v4/letter/b/c68b51/32.png) [@bobm58](https://community.cartalk.com/u/bobm58)\ **Post date:** [July 16, 2009, 2:47pm UTC](https://community.cartalk.com/t/gas-mileage/32375/3 "2009-07-16T14:47:38Z")
Thanks for the tips! Since posting I have also changed the plug wires, cap and rotor and just yesterday the EGR. We will see! ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [July 16, 2009, 3:11pm UTC](https://community.cartalk.com/t/gas-mileage/32375/4 "2009-07-16T15:11:01Z")
Blindly changing parts may or may not fix it, economically speaking. A visual inspection of the plugs (how did the old ones look?) and time on an ignition analyzer to check the coil and ignition module. However, I think you would notice misfiring that dropped MPG 24%. I would check for any vacuum leaks, loose vacuum hoses or electrical connectors, then get an engine compression test.