'04 1.6 ghia weird temp issue

I've taken a trip from the south coast to north London today and I noticed rather a lot of heat on my legs. The temperature gauge was sitting where it's always sat, just under half way but (And I don't know if I've just never noticed before) the heat hitting my legs was impressive. There was none of the usual overheating smell but I thought it prudent to open the windows and have the blowers on full.  As a side note, when actually moving the temp needle dropped nicely.

So some back story is needed here to support my issue.

About a year ago, a fire truck caught my from coner and ripped the panel, which was replaced. After it was replaced I noticed that my temp gauge wasn't working properly, a 40 mile drive and the needle didn't move. (This hasn't been an issue because it's never shown any sign of overheating and it's actually working after a fashion)

A month or so ago I was losing the low end oomph in 2nd and third so I changed the coil pack and the air filter and went to change the plugs. I discovered rusty water in the wells (I know where this is coming from and it's an easy fix) so I haven't had a chance to change those yet as I'll need to take the rocker cover off to clean the wells properly. I've got the oomph back though.

Now, this weekend I was checking stuff before a road trip and I pulled out the HT leads to see if there was still water in there (There was in 3 and 4) I put the leads back and turned her over. Misfiring in 4 and in limp mode (Also getting rather hot which I put down to limp mode) I assume there was some moisture on the plug contacts or in the lead because she was running fine the next day and has been since.

Does anyone have any idea what the problem could be?

Many thanks.