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Discussion Starter · #1 ·
hello all
1988 350 in a suburban

at idle it has... not a miss... but it almost feels like a miss/ sputter while idling IN GEAR only

like a valve is sticking

which i think is most likely

i was thinking just marvel mystery oil the motor or maybe even ATF it a bit and go from there.

these valve seals and guides are notorious for failing, because oil pressure DROPS at idle. so you need to run thick 20w50 ****.

thoughts?
anyone else have this issue? what cured it for you?

thanks!!
 

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2000 Silverado Z71 4x4 5.3L 460k+ miles w/ GM rebuilt motor and trans
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Check your fuel pressure. Marvel Mystery wouldn't hurt it.
 

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Well, as I said in your other thread, I think 20w50 is too thick, if you feel it's necessary to up the weight, try the 5w40, or the 10w40.
 

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Discussion Starter · #4 ·
i once had a stick shift i SWAPPED to a 700r4 automatic.... it would do the same thing and even die somethimes.... i think the 700r4 is just junky like that
the fuel psi was not a issue
it would just put lug on the motor while idleing
 
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