In article <77f42388.0307221331.17c1dd2c@posting.google.com >,
anna577@yahoo.com (Anna) wrote:

>I have a 93 Honda Civic hatchback, 169,000 miles.
>
>On the highway, it won't accelerate above 40mph. When the gas tank is
>full, or more than half-full, and the air conditioning is off, the
>acceleration is slightly improved. On local roads, I need to floor
>the gas pedal when going uphill, and the max speed is 20 mph.
>
>I had a tune-up 2 months ago: new spark plugs, fuel injectors, oil
>change, etc.
>
>Two weeks ago I was having the same acceleration problems, and
>starting problems on hot days and the mechanic replaced the
>distributor cap and some other work. Following that, the acceleration
>has been worse than usual, even though the mechanic adjusted the
>timing twice, 2 and 5 days after the distributor cap work.
>
>The mechanic suggested a timing-belt replacement, and replacement
>again at 50,000 mile intervals. I bought the car used at 120,000, and
>neither I nor the previous owner (also purchased the car used) had
>replaced the timing belt.
>
>Would replacing the timing belt fix this problem?
>Could the acceleration problem have something to do with the
>transmission.
>
>Thanks for your help!

Get a real mechanic. Yours is wasting your money on guesses for cures.
Such a huge power loss should be obvious to diagnose.