Yes and no, in that order.
If I read your post correctly, you say your temperature gauge doesn't read anything? So the car's not even warming up at all? Yeah, that could cause some problems for sure, just like what you're talking about. Make sure the radiator & its reservoir are full and that the cap is tested & operating properly. If the engine still won't warm up you need to replace your stuck-open thermostat. I'm willing to bet this is your problem in a nutshell.
Has your check engine light come on??? It should have, since it's probably not going into closed loop. Change your plugs & run some good fuel system cleaner (recommendation: VP Racing Fuels). Good luck.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch 
[This message has been edited by Capri306 (edited 04-13-2001).]