When i hold the key in the start position and press the gas the engine revs, as soon as i let off the key or let off the gas it dies. I have a new battery, it was running great then it all of a sudden did this. Could it be the alternator or a sparkplug/wire?. Its a 1999 dodge Durango with only 102 thousand miles on it
No. Possibly a bad idle air valve. Is the check engine light on? For how long? What are the codes stored?
Or perhaps a failing ignition switch. Do all of the dash indicators come on when you turn the key to RUN but not all the way to START?
Yes they do
Then I would lean toward Mustangman’s suggestions. IAC, MAF. Check for stored codes. Since it won’t run so you can go to a place to read the codes, you’ll need a reader. Most auto parts stores have fairly inexpensive readers.