Toyota plugs are installed (all services except this one was done at the dealer --- dealer recommended a new head gasket when there were no leaks --- did a block test. Valves were replaced 50,000 miles ago (4 years).
The engine occasionally gets rough, but nothing to complain about. I do not know what the vacuum is at this time. My co-worker and I were discussing this problem, and he thinks it might be a slight vacuum leak, and I was going to replace all the vacuum hoses for the emission system to make that no longer a possibility.
A compression check was done, and it was fine. Stupid question --- where is the diagnostic connector, and how to do I monitor that?
The reality is this car is 15+ years old, and I simply don't want to spend thousands of dollars repairing what could be something simple. If I start replacing all of these things, it could run into that amount or more. At that point, it's time for a new vehicle. As the original owner, I know how it has been maintained (very well and on-schedule).
What is "supplemental fuel", and is that added in the same method as fueling the engine??
Ok ... so where would I add this "supplemental fuel"? In the normal fuel system, or is it something I spray on? I'm a bit confused here, as this is an injection engine.
Honestly, when the tech told me he wanted to drive it back and forth to his home (45 miles each way), I almost had a heart-attack! He wanted to keep it for 2-3 days (let's see ... 200-300 additional miles on my car, and he gets a free ride back and forth to work). They were "quite sure" these were the problems, but I guess they figured wrong. I should have taken it to a dealer for the repair, but the reality is when you're lied-to without test results over-and-over, you try any available option. Luckily, I did get a good dealership recommendation from an auto upholsterer I have used in the past, and the new dealer has been great. I just don't want to pay for what has already been replaced twice; there's no way to go back and forth between Goodyear and Toyota.