fuel regulator. on the fuel rail.
MAF/MAP(app) sensor.
leaky injector.
cold start injector stuck.
general vacuum leak (typically accompanied by pinging).
t-belt issue-non-interference engine.
i would not think it's an ignition issue. that tends to be more evident @ rpm as the coil has less time to saturate.
----------------
or pull codes. don't need a scanner tool. the check engine light blinks.
how to get it to blink at you,
http://www.autozone.com/autozone/rep...00c152801ccc63
clearing and reading codes,
http://www.autozone.com/autozone/rep...00c152801ccc73
that info is the same for the I4 or V6. if you need to nav from that page you need to sign up, plug in vehicle info, and go to "repair info"
it's free!