i have a 99 cherokee with a 4.0L about 130,000 miles.. about 60 seconds after i start it it will start spitting and sputtering while its doing this you can hear it sucking alot of air. if i give it gas it will rev like it should but if i hold it steady it falls on its face.. after a few minutes of this it seems to run and drive ok.. this happends hot or cold everytime. and ideas would be great thank you!