After 20 miles, Festiva loses power

[blackaley]

I have a 88 Festiva that has been running great until recently. After running for about 20 miles or so, the engine begins to lose power. Upon downshifting into a lower gear it continues to lose power until I shift into second or third gear. Then all of a sudden it regains its power although it does not seem to regain all of its power. I have replaced the plugs, wires, pcv valve, distributor cap and button, fuel filter, and air filter. I have also tried putting gas treatment thinking it may somehow be water in the gas. I have also sprayed the carburetor with cleaner hoping it may help. I am kinda out of ideas so any help would be appreciated. Thanks.

[packrat427]

Are you saying it just loses power ,like it shuts off and coast a bit then comes back on ,
Or it loses power and it still accelerates or maintains , just down on power , but will not gain any speed .

[blackaley]

It seems the engine bogs down as if possibly putting on the brakes. Upon pushing the clutch in, the engine can be revved up and seems to run fine. But when you release the clutch, the engine bogs down again.