I seem to get these codes every so often.Vehicle has 166k miles and codes appeared.Vehicle runs fine now,checked codes with scanner and then cleared them.I have owned vehicle since 2003.Plugs ,cap and rotor were changed at 130k.At 141k,got #5 missfire,so I pulled the plug checked the gap and put plug in #3 hole.At 154k,I decided to remove ignition module,clean the back side ,install new dielectic silicone and reinstall.I had no problems for 25k miles.A new fuel pump and in Dec 2011 a new fuel filter was installed.There is only two common occurances that I have noticed.When it is excessively damp out,the code appears and just after I have fueled up and headed on the highway.I have read about worn distributor drive gears.Would this not put a cam to crank correllation code?How much back lash is acceptable for the drive gear?This is what I am looking at,but without a correllation code,I am questioning that solution.I am also wondering if my ignition module could be at fault due to age, temperature breakdown and that I don’t believe there is a specific code for ignition module failure . I am excluding the fuel injectors because I think they would give a code much faster.My ignition wires haven’t been changed,but I’m not convinced they may be the culprit. With the mileage that is on the vehicle,would an intake manifold gasket leak be an issue?It has never been done since I owned it and don’t think it was done by previous owner.Sorry for the long sad story,but this vehicle has been great other than this issue.Help would be greatly appreciated.

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random & #5 missfire 99 burb