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i have a 5.0 v8 out of a 89 f150 in my mustang and it has started to slowly increase the idle as time goes on starts out at about 1500 and increases to about 2000 when it warms up shows a code for the idle air control and the throttle pos. sensor but they are both in limits no apparent vac. leaks either should i just start replacing sensors other than this it runs [email protected]
 

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I had this problem with one of my '91 5.0s. It turned out to be a bad throttle position sensor. I replaced it once and it didn't help, I then replaced some of the o2 sensors as suggested by the dealer, but that didn't help either. I replaced TPS again and it was fine after that. I think Ford has had a problem with some of the TPSes.

It's been a few years since I've messed with 5.0s so I'm a little rusty, you might check out www.corral.net or www.dfwstangs.net and ask the 5.0 crowd what they think.
 

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If you are geting a TPS code replace it.The processor looks at the lowest TP reading and assumes it is closed throttle.So if your TP is going open intermitantly you will experiance a high idle because the processor thinks it is at part throttle and stratagy keeps the IAC open further.
 
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