Having trouble with SERIN command and MAX6675

[Bruce]

Have you tried sending the raw value received 'without modifying it' to your LCD while heating or cooling the part?

Something like: lcdout $fe, $c0, BIN16 MXtemp

Does it change when heated?

Edit: Since you're using the internal osc on this one, place Define OSCCAL_1K 1 in the top section. Not sure it that will fix it, but it will for sure affect timing.