If you still have the metal coolant pipe assembly in place,which has both heater hoses connected to it at the firewall end,you need to pull the heater hoses off of it then connect a U shaped hose or two straight hoses with a U shaped pvc/copper,etc pipe between them.The ect sensor resides in the supply side of the coolant pipe assembly and the egr spacer coolant supply hose resides in the return side of the pipe assembly.The ect sensor needs to remain in its original location,so that coolant can flow around it,making for a better reading.If you have caps on the firewall end of the pipe assembly,instead of a U shaped bypass
hose,coolant will be stagnant instead of circulating and the ect sensor reading will be off most likely.The ect sensor has a huge influence on fuel mixture and timing,so its important the sensor reads true coolant temp,which requires its mounting location to be the original.If you remove/have removed the coolant pipe assembly,the same hole thats used to screw the pipe to the intake,is the same hole you should use to screw your ect sensor in place.
Another thing you need to check is the secondary ground.Its the flat braided strap located between the cylinder head (rear) or intake & the firewall.Its the ground for the interior/exterior lights,ac clutch,alternator & the gauges.If the secondary ground is loose,corroded or disconnected,the temp gauge will spike anytime accessories (blower fan/ headlights/etc) are turned on,so make sure that ground is intact ................
91 LX 342ci (10.5:1)
TFS 190cc (stage ll)
GT40 (tubular) intake
Weld ProStar XP's