Rough start when warm/ misfire

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Nov 30, 2016 | 02:56 PM

Louie96

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Joined: Nov 2016

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Rough start when warm/ misfire

Hey guys! I've been trying to do a lot of research on this site but can't get the answer I'm looking for, so I here I am. So to start I have a 93 f-150 short bed single cab with the 5.0 5 speed 4x4. Engine has only 72k on it but was rebuilt. Body has 172,000. When I start it up cold she runs awesome but it has just a slight random "bump" that feels like a misfire but it's completely random. Like it's not one set cyclinder. Also when it's warm and it's been sitting for around 15 to 30 minutes, I got to start it and it fires up but has a real rough idle and it fluctuates. Now the parts I've replaced in the past month are the egr valve, iac, airfilter, plugs, cap and rotor. Could it be a weak spark? I forgot to mention when I got the truck the guy before me had the engine steam cleaned and got moisture in the distributor. When I test drive it it was missing like a b**ch. cleaned and dried the cap/rotor and it was fine. What do you guys think?

Dec 1, 2016 | 11:19 PM

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Joined: Jul 2007

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From: Rhode Island

These engines are very prone to cross-firing through the spark wires for whatever reason. There's a certain way you have to route the wires to prevent that from happening.