Engine Foxbody idling surging and stalling

That_White_Fox

New Member
Apr 16, 2020
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Hello,

I have a 89' foxbody and I recently took apart the upper manifold and cleaned all ports, put it back together and it idled in the 1,500s without coming down for 30 seconds. I went ahead put a new IAC and TPS, and adjusted the idle down to 800 RPMs. The car didn't run good after any of this, now it surges under idle after a minute or it will stall out. As of lately it's been eating oil, and I've been finding oil inside the IAC. I fired it up one day after I adjusted the new TPS to .98 and it smelled really strong of raw gas all through the ports. Out of ideas now.

What I've done:
I changed 75% of the vacuum lines, don't know what else is left.
Put a brand new gasket on upper
Replaced distributor cap and rotor

The car still runs poorly after, I don't know what else it could be, I ordered a new EGR valve and new plug wires because my headers burnt one wire. Possibly gonna order new O2s unless someone says otherwise. The codes I got were 15, 63, 67. The car has bolt ons, it has heads, headers, X-pipe, intake, and a bama tune. Need help, loosing my mind over here.

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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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Do this step by step, take notes, any questions post them and the members will help you out.
 

FoxMustangLvr

I love my Pimp
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Oct 14, 2012
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The checklist that Karthief posted is the best source of information out there. I absolutely stress the importance of following the checklist in order and do not skip anything. Do not assume something is OK and do not just throw random parts at it.

Good luck
 

Potomus Pete

Gretchen Whitmer is eating at me
Mar 7, 2019
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Thats why I never take my under hood apart for the fun of it anymore. About once a month I make sure everything is connected , and thats it. These cars break to easy ,even after fixing all kinds of stuff I still get loose stuff.
 

That_White_Fox

New Member
Apr 16, 2020
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Do this step by step, take notes, any questions post them and the members will help you out.

Will do, I've already been going through the checklists, appreciate all the help, I almost wonder if it isn't my EGR valve, replacing it in 30 mins and going to see if this fixes anything. Thank you
 

That_White_Fox

New Member
Apr 16, 2020
5
0
1
20
California
The checklist that Karthief posted is the best source of information out there. I absolutely stress the importance of following the checklist in order and do not skip anything. Do not assume something is OK and do not just throw random parts at it.

Good luck

Too late for that hahaha, I've already been throwing parts at it, mainly because they are due and need to be replaced too. But thank you for the help I appreciate it, and keep you and general informed.
 

That_White_Fox

New Member
Apr 16, 2020
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I got new o2s and it made a difference in acceleration. A pretty good dif. I bet your sucking air from some place.

Looking back, yes it wasn't a good idea but at the same time I'm happy I did because there was so much build up inside the manifold it was disgusting. But yea I see the point, I'm going to do O2s next, hopefully that and the new fuel pressure regulator I'm putting on solve the raw gas smell. Thank you guys, appreciate all the information fellas. :)
 

Potomus Pete

Gretchen Whitmer is eating at me
Mar 7, 2019
1,342
456
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Sarasota Florida
If it ran before than its something simple no doubt. Loose wire or vacuum . Sounds like you have your hands full. Tell us what it is.
 

That_White_Fox

New Member
Apr 16, 2020
5
0
1
20
California
If it ran before than its something simple no doubt. Loose wire or vacuum . Sounds like you have your hands full. Tell us what it is.
Alrighty man, yea I'm replacing the gaskets on the TB and EGR housing but 1 of the bolts were locked and wasn't giving in so about 7 knuckles and 6 flat heads later I had to grind off the stud. Which leads me to the next question for everyone. Does anyone have a trick flow or a GT40 they can sell me for cheap because mine is toast. :(