Engine loses power sometimes when not warmed up, sometimes after traveling awhile on 1997 Kia Sportage

The engine needs to be warmed up or else it loses compression, as if it is in 2nd gear, & needs to be turned off, restarted & then it can go. Sometimes this can also happen while traveling for awhile, after letting off gas & then trying to accelerate again. Any thoughts on what this could be?

Asked by for the 1997 Kia Sportage
check your coil and also plugs and wires