Welcome to the forum and to your new adventure…..lol.
First things first….when oils are overfilled, they no longer lubricate, so the first thing I’d do is change your tranny fluid, and get it down to the proper fill mark. The way to properly check the level is to have the car on level ground, and get the engine to proper operating temp. Then move the gear selector to all gear positions, and then back to park. Then check the level. It may be that the tranny problems you are having are beyond the scope of this forum, and that even changing the fluid may not help. But getting the fluid to the proper level is a good place to start. However, it is strange that you no longer have the TCC solenoid code??
Your P0135 code will have nothing to do with the temp gauge moving about. Normally the O2 sensor has a life expectancy of about 100,000 miles, so if it’s never been changed, it’s a good idea to do so.
As the car is new to you, it’s a good idea to change all fluids (coolant, oil, diffs, tranny, t case, etc.) and filters To start off with. I’d also do a compression test on the engine, just to verify engine timing. Check that the spark plugs are gapped to .7mm (or replace, if needed). Check vacuum lines for leaks (which might cause the hunting idle) by pinching each of the vacuum lines with a pliers. Other than the idle speed solenoid, you should not have a change in idle with any of the lines pinched. While these things may not correct any of your issues, it’s a good idea to get the engine in ‘factory’ spec, and then diagnose from there.
It’s also a good idea to get a proper scanner, rather than a code reader. A scanner will give you real time data, rather than just the code numbers.
First things first….when oils are overfilled, they no longer lubricate, so the first thing I’d do is change your tranny fluid, and get it down to the proper fill mark. The way to properly check the level is to have the car on level ground, and get the engine to proper operating temp. Then move the gear selector to all gear positions, and then back to park. Then check the level. It may be that the tranny problems you are having are beyond the scope of this forum, and that even changing the fluid may not help. But getting the fluid to the proper level is a good place to start. However, it is strange that you no longer have the TCC solenoid code??
Your P0135 code will have nothing to do with the temp gauge moving about. Normally the O2 sensor has a life expectancy of about 100,000 miles, so if it’s never been changed, it’s a good idea to do so.
As the car is new to you, it’s a good idea to change all fluids (coolant, oil, diffs, tranny, t case, etc.) and filters To start off with. I’d also do a compression test on the engine, just to verify engine timing. Check that the spark plugs are gapped to .7mm (or replace, if needed). Check vacuum lines for leaks (which might cause the hunting idle) by pinching each of the vacuum lines with a pliers. Other than the idle speed solenoid, you should not have a change in idle with any of the lines pinched. While these things may not correct any of your issues, it’s a good idea to get the engine in ‘factory’ spec, and then diagnose from there.
It’s also a good idea to get a proper scanner, rather than a code reader. A scanner will give you real time data, rather than just the code numbers.
