Elusive misfire

Hello,
Vehicle is a 1995 Pontiac Grand Am SE, four speed auto, 2.3L "Quad Four" engine.
The other day it pops up with the SES light. I had the codes read and it
says "Engine misfire detected cylinder 4, dejected" I suspected a misfire by ear before, and now the computer is picking it up. One by one, I've replaced the spark plugs (twice), spark plug boots, coil housing, and both coils. None of it has worked.
Some details of the symptom. It will not misfire when I start it up, and it won't misfire while cruising down the highway, or if you step on it. The first time that it picks up a misfire is after it's all warmed up, and you come to a stop. Most of the time it is just as I ease into the gas.
Now...... I'm stumped, and tired and exhausted with trying to figure it out, while spending money.
Any ideas appreciated.....
Tony
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Tony wrote:

Spark plug wires?
---Bob Gross---
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No, actually it has no spark plug wires. The spark plug "boots" are a rubber sleave inside a plastic case, with a spring inside that act as spark plug wires. I've replaced those.
But thank you for the suggestion.
Tony
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Tony wrote:

That's pretty funny! The spark plug wires don't have copper conductors inside, but they are conductive nevertheless. The boots are the short pieces on the end where it connects.
---Bob Gross---
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You said the coils were replaced - has the actual IDI ignition module been replaced?
--
Robert Hancock Saskatoon, SK, Canada
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No, the module hasn't been replaced.
Be aware, I'm not entirely sure exactly how that module operates. It only has two prongs in the connector that goes to one coil, then the other. It looks as though it simply sends voltage to both coils when needed. My misfire is "only on cylinder 4" according to the ECM. I could be wrong about the modules operation though.
I'm also tired of spending money and not getting it fixed, but I may have to.
Thanks,
Tony
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It would be valuable to check and see if you're getting any misfire counts on #1 as well, that's the paired cylinder to #4. If so, then quite likely it is the module. (I don't know if you can see misfire counts on a generic OBD II scanner or not..)
It's possible it could be a fuel delivery problem, like a bad #4 injector..
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Robert Hancock Saskatoon, SK, Canada
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Well, I talked with my mechanic today. And Friday I'm going to drop it off with him. He's going to hook a scope machine to it and do a leak down test. We'll get to the bottom of this yet. I'll post my (his) findings as soon as I know. Tony
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Okay, it wasn't even a misfire. I feel like an idiot. Although it could have been to start with, I don't know.
Anyway, the cheap-o-scanner they had at the local parts store may have given me a bogus code. Turns out there was a short in the wiring to the IAT sensor. (Intake air temperature) It was reading -58 degrees!!! Constantly! So of course, the engine was getting a flood of fuel. Which could cause a misfire due to excessive fuel and timing advance but that's not what their scanner read.
All in all, I made out cheap, and got it fixed. Whew.
Tony
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This is a perfect example of getting a GOOD code scanner so that unnecessary repairs are not perfromed and the problem is resolved quickly

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