HELP - Crown vic overheating......lost

I have a 96 crown Vic, 4.6L V8 CNG. Running hot lately and i replaced the themostat and coolant sender. I noticed the temp guage in the car would not work then after a few minutes shoot up to HOT!. I replaced the sender last night and now the temp gauge doesnt work at all so i am really lost. What else could it be ? what else could i check b4 i have to take it to a shop? also had a P0125 error code a few weeks ago and just made sure it had enough coolant and light went off.