BamaJohn, just putting in a 160 stat will not do much, the stat will just open earlier, and the temps will still rise. You need to do two things, first make sure your radiator is clean, mine did not look bad at first but looking through it with a drop light behind it showed about half the fins had sand stuck between them. The second thing is to have the fans turn on earlier, there is two main ways to do this. One is to install a low temp fan switch this goes in the driver side head, a 91 has a plug in the head, I tried several times to get it out with no luck that thing is in there. The other way is to have the chip programming changed, this is what I did. I had mine changed to have both fans come on at 190 and off at 180. That with a 160 stat made a huge difference, mine would shoot up to 230 in traffic, which made me nervous, now the gauge stays right around 1/2 way, since a 91 does not have really have numbers on the gauge I can't give you exact temps.
You can probably find someone here that will change the settings in your chip for a few bucks.
Good luck.