Hey guys I'm in a Shitty situation! My ranger has 219 k miles and about 25 k on the rebuilt motor. All of a sudden my truck was throwing a code for cylinder 3 misfire (p0303) and a pending trouble code for system running lean (p0171) . I ran tests and even the shop did too and determined it to be somesort of sticky valve. Before I brought it to them though I sea foamed it and it was running much better because it used to stall but then the sea foam seemed to help but then it came back again. So I brought it to the shop and we went a cheaper alternative to the pulling the head off and finding the problem by doing an engine flush. And it ran like a champ for a good week or two but then of course it came back. While i was sitting at t-bell I felt the truck idle changing like every few seconds then my ultragage and truck quickly threw a code for the misfire. (Wasnt even a pending first) and it also showed the lean as pending. But now my truck I can feel it as like a power struggle (like as if I was stepping on and off the gas) at low rpms/idle but at high rpms I don't feel it. I think its the springs but idk. I dint wanna dump another $1700 into it. Hellllppppppp!

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1997 XLT Supercab 2.3L manual with 4.10rear
2.5 exhaust throughout with Flomaster 40 Delta
216k miles

when you did the rebuild did you replace valve springs, seats, guides? Also I know you said you ran tests did you test your injector?

I'm not positive on the valve stuff. I brought it back to the guy who rebuilt it and he tested the injectors, Egr, maf, replaced plugs and wires and he says its none of them and that its not the valves. Yesterday he was checking out the valve springs and I should hear from him today.

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1997 XLT Supercab 2.3L manual with 4.10rear
2.5 exhaust throughout with Flomaster 40 Delta
216k miles