1993 Toyota Camry TEMP

My car never seemes to "warm up" it always stays on cold except when it is in park, when its in park the car's temp seems to go in the middle where its supposed to be and my heat works like it should, but when I take it out of park my heat doesn't work like it should. The temp drops back down to the C.

also my I think my car needs a tune up. Becasue when it runs like when im on the highway driving not the odometor but the thing next to it which goes form 1-like 8 or 9 it goes up the the number 4 and I can hear the engine working. I recently had to fix racka nd pinion part which all together including the labor cost me 600 dollars. I jus go the car so I havn't done anything to it and the previous owneres never drove the car it just sat there.