Dear Tom and Ray:

My 1984 four-cylinder Toyota Camry experienced a time when it would lose power on the freeway, especially when going up long hills. It would eventually stall, then immediately restart. Following the advice you gave another Camry owner, I had the dealer run a detergent through the valves to clean off the carbon. That fixed it until recently, when the problem started to come back. Do you have any other ideas? -- Rich

TOM: Sure, we have lots of ideas, Rich. Ideas are easy. Knowing what's actually wrong with your car ... that's a lot harder.

RAY: You don't say how long ago is was that you had the valves decarbonized. You may simply need to do it again.

TOM: Older Camrys are prone to collecting carbon deposits on their valves. After 80,000 or 90,000 miles of driving, carbon cakes up on the engine's valves and
prevents them from closing all the way. And you notice the loss of power first under load (when you're making the engine work its hardest -- like climbing hills at high
speed).

RAY: But there are other things that can cause the same symptoms, like a failing fuel pump, a clogged fuel filter, a plugged catalytic converter or a weak ignition coil
that isn't delivering enough spark. And all of those are possibilities on a 15-year-old car.

TOM: So what's the moral of the story, Rich? There are times when you just have to go see a mechanic. And never, ever diagnose your car solely via a couple of jerks
writing a newspaper column!