# 1991 suburban rough at minimum throttle

**URL:** <https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620>\
**Category:** Maintenance/Repairs\
**Created:** [May 30, 2013, 12:59am UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620 "2013-05-30T00:59:26Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Corvanman](https://avatars.discourse-cdn.com/v4/letter/c/e47c2d/32.png) [@Corvanman](https://community.cartalk.com/u/Corvanman)\
**Post date:** [May 30, 2013, 12:59am UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/1 "2013-05-30T00:59:26Z")

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I have a '91 suburban (1/2 ton, 5.7 TBI) starts,idles and revs great, stumbles at most minimal throttle(parking lot speed) replaced cap, rotor, plugs, wires, filters. Ran injector cleaner thru it, swapped TBI with a known to be working unit… I’m lost!! HELP!

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**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\
**Post date:** [May 30, 2013, 2:18am UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/2 "2013-05-30T02:18:45Z")

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Cleaning the mass airflow sensor comes to mind as a worthwile inexpensive thing to try.

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**Author:** ![Corvanman](https://avatars.discourse-cdn.com/v4/letter/c/e47c2d/32.png) [@Corvanman](https://community.cartalk.com/u/Corvanman)\
**Post date:** [May 30, 2013, 2:34am UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/3 "2013-05-30T02:34:00Z")

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No mass air flow on 1991

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**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\
**Post date:** [May 30, 2013, 2:45am UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/4 "2013-05-30T02:45:30Z")

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Did a parts search and it seemed to be out there, good catch. Have to revise to bad injector, 02 sensor or pcv valve as my wag.

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**Author:** ![Corvanman](https://avatars.discourse-cdn.com/v4/letter/c/e47c2d/32.png) [@Corvanman](https://community.cartalk.com/u/Corvanman)\
**Post date:** [August 1, 2013, 7:35pm UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/5 "2013-08-01T19:35:07Z")

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Anyone else got any ideas

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**Author:** ![Rod-Knox](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Rod-Knox](https://community.cartalk.com/u/Rod-Knox)\
**Post date:** [August 1, 2013, 8:41pm UTC](https://community.cartalk.com/t/1991-suburban-rough-at-minimum-throttle/79620/6 "2013-08-01T20:41:17Z")

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Check the timing and TPS.