Will lower degree Thermostat effect ignition timing?

I have a 1996 blazer, 4.3l w. I just recently rebuilt it, in fact I put it back in a week ago today. I di put a comp cam and made some mods to the valve springs and rocker arms, basically to handle the lift and put adjustable rocker arms on. At first I had a Jet stage 2 chip on the engine and it called for a 160 degree thermastat, I had since taken the Jet chip off because the chip was not designed to go on modified engines and the manufacture said it wasn't such a good idea. Well, I left the 160 thermastat in when I rebuilt it and just doesn't feel as responsive as I think it should. I have a scan tool and it is reading a "Adv timing degree" of -30 to -19. My question is will the computer still go into open loop if it never reaches the stock temp that is set? And if so could that be affecting by ignition timing? Thanks for any help you can give![/B]