I just replaced nt thermostat with a 160 degree t-stat. Now the problem is my fan does not turn on until normal operating temp around 190 -210 degree.

does anyone know how I can get the fan to kick on sooner, with the t-stat, around 160 degrees?

Isn't the specified thermostat 190 - 195 degrees?
Anyway, the electric fan on '99-'04 models (in models where the electric fan is the primary cooling fan) turns on in the 190 -210 degree range.
As for getting it to turn on earlier, I don't think it's possible short of reprogramming the PCM.

yes the specified t-stat is 195, but I went with a colder t-stat to help keep the engine cooler when running the a/c.

Not sure but on a Chevy car my buddy had he did the same thing, put in lower thermastat and the electric fan still kicked on at the normal operating temp of about 190. He was able to buy the thermastat sensor that kicks the fan on at a lower temp from a local parts store. Might try checking into that, reprogramming the PCM shouldn't determine what the sensor is set to let electric current flow through it to allow the fan to come on, not positive on that though, just a thought.