Getting 301 and 307 codes

Have you checked for a broken valve spring. Repaired a dodge engine with the same running issue as you have described and it was a broken intake valve spring.

I have a 98 punto sporting nd today it started running like it was misfiring but wen i accelerate slow its fine but wen u accelerate as normal it spits and splutters :'( any suggestions??i have change fuel filter nd injectors ????

Does it come out of overdrive or down shift when the RPM drops ?

I have seen this problem and it is very often a problem with the engine wiring harness, where that may lie is anyones guess, look at places where the harness moves around allot.

I would try running the codes it may have bad throttle position censor

do a code search check codes on yahoo also go to youtube and finde code search vid

change the trans filter

sounds like you have a bad alternator the alternator generates power from the engine which in turn keeps the spark plugs firing (and all other electrical components) the higher the rpm the more power you can generate up to about 3500 rpm or so I suggest removing the alternator and bringing it to your local auto parts store to have it tested I would also bring the battery and have it charged since you don't want to put a new alternator with a less than full charge on the battery (you can damage it) WARNING:On older vehicles it was common to check the alternator by starting the engine then removing the battery terminal ... (if the engine died the alternator as bad) However on newer vehicles you could damage more important and expensive electrical components including the computer or brain of the vehicle.

Does temp gauge go up when this happens ? When was fuel filter changed last? If not recently, I'd start there.

Check/change the egr valve. They have been know to be culprits.