Actually I just noticed the rubber plug was pushed in for the engine harness as it goes through the firewall! Not sure how or when it happened but it is reinstalled now.

I am thinking the whole rain thing may have been a coincidence as there was not lots of water around the engine, yes there was moisture in the cap but that may not be so unusual in FL.

Water in the splice for the O2 sensor may be another story, although I think I did a pretty good job of shrink wrapping and sealing the splices. I'm guessing my crush splices were not very good as I do not have the correct tool. What is a good brand tool?

I soldered on a new Bosch 13913 this time and sealed and shrink wrapped it the best I could. I have spliced 6 or 8 of these sensors over the years and this was the first problem. From now on I will take the extra time to solder these connections.

I will check out the TB post, thanks for letting me know.

The waiting game begins, how long will it run this time without the stumbling and backfiring coming back. I am really hoping I am done!

I did monitor the voltage on the new sensor when I started up and it looked real good .5 volts for a few minutes to the closed loop of about .3 to .9 v.

Thanks again
Dan