Question about 1991 Ford F150

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1991 f150 idles rough but when u give it gas it gets better

Rough idle when in park when u put in gear it gets worse but once u take off it ildes smooth

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  • 13 Answers

Here are a few things that might help.
1. Check your spark plugs. make sure the gap is right and they are not worn out.
2. Check your distributor cap and rotor for build up on the contacts.
3. Check your spark plug wires, make sure they are on the distributor and spark plug tightly. also check them for damage ie. heat, knicks, scrapes, etc.
4. intake idle control valve. these do cause your symptoms and are easy to replace.

hope this helps ~ Zach

Posted on May 21, 2014


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Posted on Jan 02, 2017



  • 85222 Answers

SOURCE: ROugh idle

there are 2 things that usually cause this, one is a dirty intake idle control valve and the other is hard engine mounts, I would say that both most likely apply to your car. try cleaning the intake with the following procedure from Ford.
Here is the most common cause of surges and stalls and low idle rough idle, it is the idle speed control air-bypass valve and throttle valve (IAC for short), they get full of gunk over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

Posted on Feb 18, 2009


SOURCE: rough idle when sitting at a red light until van warms up

change plugs

Posted on Oct 20, 2008


  • 16 Answers

SOURCE: Idles rough when cold

the throttle body is icing. there are engine coolent lines running to the intake plentum. flush youre cooling system and see if that fixes it

Posted on Dec 30, 2008


  • 15 Answers

SOURCE: engine cuts out or bogs down when accelerating

if the engine light is flashing, it means you have a misfire in one or more cylinders. it is most likely plugs or coil wires.
mine started doing this a few weeks ago. finally got around to changing the plugs today. the cylinder order on fords is easy, passenger side from front to back is 1234, driver side front to back is 5678. my number 4 cylinder had a plug that was collapsed. the metal piece was crushed into the contact, not allowing any spark.

Posted on Jul 13, 2009

Richard Delahant

  • 1201 Answers

SOURCE: 2001 Ford E150, V6. Stutter/hesitation upon

Have the throttle position sensor checked, might be faulty.

Posted on Oct 01, 2009

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Hi and welcome to FixYa!

Looks like that you have a faulty TPS (throttle position sensor). If the TPS is faulty you'll have a rough idle when in drive even worse during cold start ups. It is located on the throttle body. Have it replaced and you'll be good.

Hope this helps and thank you for using FixYa! Have a good one!

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