# Sputtering issues **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** pickup, gmc\ **Created:** [October 10, 2017, 3:14am UTC](https://community.cartalk.com/t/sputtering-issues/108496 "2017-10-10T03:14:37Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Bullrider4](https://avatars.discourse-cdn.com/v4/letter/b/3ec8ea/32.png) [@Bullrider4](https://community.cartalk.com/u/Bullrider4)\ **Post date:** [October 10, 2017, 3:14am UTC](https://community.cartalk.com/t/sputtering-issues/108496/1 "2017-10-10T03:14:37Z")
I have a 1993 gmc k1500 4wd with the 5.7 throttle body when I hit the gas and let off the rpms bump up and down it acts like it’s wanting to die but then catches its self it only happens after I let off the gas I changed all my IAC and the throttle position sensor so I’m running out of ideas. ---
**Author:** ![oldtimer-11](https://avatars.discourse-cdn.com/v4/letter/o/e79b87/32.png) [@oldtimer-11](https://community.cartalk.com/u/oldtimer-11)\ **Post date:** [October 10, 2017, 4:01am UTC](https://community.cartalk.com/t/sputtering-issues/108496/2 "2017-10-10T04:01:35Z")
It is really hard to figure out what you ate saying without punctuation. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [October 11, 2017, 1:02am UTC](https://community.cartalk.com/t/sputtering-issues/108496/3 "2017-10-11T01:02:27Z")
When an engine acts like it wants to stall immediately after pushing on the gas pedal, that makes me think it is running lean. The extra air from opening the throttle plate is enough to go from running lean to not running at all. Sinc eyou’ve already eliminated the throttle position sensor and the IAC I’m thinking you have some kind of vacuum leak. Make sure the brake booster is holding vaccum, and if you have an MAP, check that holds vacuum too. After that you could try spraying some starter fluid here and there . If the engine revs after a spray you’ll know there’s an air leak into the engine in that area. Make sure there’s not air leaks at all in the components between the air filter and the throttle body too, as that can confuse the engine computer.