91 2.2 L accord help

i have a 91 accord 2.2L with an unusual problem i cant figure out and need some help from you tuners. i can start it cold no problems it will tach up no problem, it will only stay running for 20-25 minutes and them dies? then it takes awhile to get it fired back up, when it finally gets fired up it runs rough and will only tach to 3500 rpm even if i hold accel. to the floor it will only reach 3500 rpm and spits and cuts out and sputters. i have driven it like this and it seems to lack power. any suggestions would be helpful and appreciated very much. thank you dave.