for vac leaks idle the engine and spray carb cleaner at the vac lines, if the idle jumps up you found a leak.

the temp sensor could be covered in dex sludge messing up its readings or its on its last legs so to say.

coolant is full and air is bleed out right?

it could be fuel, check the line pressure at the rail. you can get a free rental at the local parts stores. you leave a deposit on the tool, they refund you in full when you return the tool.