Speedometer, tack, fuel gauge, temp gauge have erattic behavior

loos connection somewhere

PO116 Engine coolant range tempreature circuit.
I would change the temp sensor and first make sure the coolant is full in the rad with no air in the system.

from the sound of it then its a complete new speedo head unit if its one of the newer type say more modern than a 2000 .And OUCH its not cheap so try a scrap yard

try resetting the service lights

the indicator in the dash is faulty

Hello! This is actually a pretty common issue on the '04's - and I've had it myself. There was a TSB put out about it, in fact. Here is the info from the TSB:

Subject: Speedometer Erratic Movement, Fuel Gauge Does Not Go to Full After FIlling, Engine Coolant Temperature Gauge Reads Hot and Coolant Temperature Light Illuminates (Reprogram IPC) #05-08-49-003A - (04/18/2005)

Models: 2004 Pontiac GTO Built Prior to VIN Breakpoint 4L296011
Condition Some customers may comment on one or more of the following conditions:
• Speedometer jumps erratically. Gauge may go up to 200 MPH or not return to zero. • Fuel gauge does not move off empty when tank is full. • Engine coolant temperature gauge reads hot and coolant temperature light illuminates. These conditions may be intermittent.
Correction Technicians are to reprogram the IPC with an updated software calibration. This new service calibration was released with TIS satellite data update version 1.0 available January 10, 2005. As always, make sure your Tech 2® is updated with the latest software version.
Important: Vehicles built after the VIN breakpoint must have the IPC replaced to correct these conditions.
Warranty Information For vehicles repaired under warranty, use:
Labor Operation
Description
Labor Time
N4199
Instrument Panel Cluster (IPC) -- Reprogram
0.4 hr

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

Check fuses first.

The Body Control Module is the problem.Models with black faced gauges are most noticeable. Also,on rainy,foggy,or overcast days, the headlights will come on,but the instrument panel lights do not.GM states these condition are "normal" and refuses warranty service-Document ID# 1530511

Fuel pump

I think the ford 350 might be a loose ground wire. This can cause the erraticness within the gauges.

The windstar is a faulty sensor switch on the brakes master cylinder. It leaks brake fluid into the wires that are connected to it causeing a short circuit and resulting in a blown fuse that powers the AC, cruise control, odometer, speedometer and the ABS light to remain on. This issue can also cause a fire. This fire can occur even when the car is off. To fix the problem go to this URL - http://www.fordwindstarrecall.info/