PSP question- editing skies

I'm using PSP 7 and I'm converting some pics to the doom palette to make skies and they convert okay but sometimes I want to tweak them and whenever I do it switches from the palette again and then I switch back and things are a bit off,

Is there a way to make sure that I'm only adjusting by colors in the palette?

I suppose I could manually color replace from the palette, but this could be really tedious. if anyone can give tips on this I'd be very grateful, cause I know I can make a lot of these textures workin the palette with some modification.

Here is an example, I have a picture of a purple sky that turns goes to gray upon conversion instead of using the new palette's purple, which would work fine, I know there would be less shades, but that doesn't matter, these aren't hi-res.

There are a couple things chaotic but I'll attempt to help You.

but sometimes I want to tweak them and whenever I do it switches from the palette again and then I switch back and things are a bit off,

I completely don't understand this. What do You mean by tweaking-in XWE? In PSP? If the latter-just apply "milion colors" (by ctrl+0) and do Your stuff and re-apply the pallette.

Is there a way to make sure that I'm only adjusting by colors in the palette?

Unfortunately, if You're not working in 256 bit then no. I presume You mean working in 32 bits and then checking out if You're using only the colors of the pallette, right?

I suppose I could manually color replace from the palette, but this could be really tedious.

Not really if You play with "tolerance" values in the tool's settings. Check the various tabs.

Here is an example, I have a picture of a purple sky that turns goes to gray upon conversion instead of using the new palette's purple, which would work fine, I know there would be less shades, but that doesn't matter, these aren't hi-res.

Being hi-res or not has nothing to little to do with pallette applying to be honest (except scaled hi-res things tend to look decent if the pal is applied via error diffusion.. anyway). I'd need to see the graphic and the pallette to help because it sounds like the colors of Your picture don't match the colors of the pallette. Mess with the picture's colors' saturation, hues, values and such to make them close to the pallette. Then they should match each other rather fine.

An pictoral example (since we're on subject of visual graphics ;) ) would be best here.