I need to check the grounds you mention. I took a closer look at the gauges while warming up in the driveway. I graphed the ECT on my scanner and it was going up fairly nicely and then got jumpy. The oil pressure gauge also got a bit jumpy. Along with checking those grounds I wonder if I can/should run a aux. ground wire from the block near the ECT to the computer ground point would be an idea to confirm I have a ground issue? Also I can find on ALLDATA which module the ECT wire goes to - I assume the main engine module up by the battery and alternator.
I wonder if there is a bubble in the coolant. I need to look for the proper purge technique.
This from Haynes:
Refilling
12 To refill the system, install the thermostat and reconnect any radiator hoses.
13 Place the heater temperature control in the maximum heat position.
14 Be sure to use the proper coolant listed in this Chapter's Specifications. Slowly fill the surge tank with the recommended mixture of antifreeze and water to the FILL COLD mark.
15 With the surge tank cap off, start the engine and let it idle for about a minute.
16 Install the cap on the surge tank, but don't tighten it down (pressure must be able to escape). Raise the engine speed to approximately 3000 rpm in 30-second cycles until the engine reaches normal operating temperature and the thermostat opens.
17 Turn the engine off and remove the surge tank cap. If there is any hissing noise coming-from the tank, wait until it stops then remove the cap.
18 Start the engine and let it idle for one minute. Add coolant to the tank until the level is 1/2-inch above the FILL COLD mark, repeat Step 16, then turn the engine off.
19 Add coolant as necessary to bring the level to 1/2-inch above the FILL COLD mark on the tank. Install the surge tank cap securely.
20 Check the cooling system for leaks.
