I have a 98 nissan altima with the service light on. While at idle or driving the car sputters and bogs down.when I press the gas pedal a few times in pick and kicks in, but then does it again.
Any suggestion

. Reset the ECM by disconnecting the negative battery terminal for 10 seconds and see if the problem improves. Record any radio codes first.

. Attach a code reader or scan tool to the data link connector under the dash, in order to find out what codes are being thrown. The codes will send you in the direction of what's wrong. Find out if a local auto parts store will do this for free or buy an inexpensive code reader.

. Ensure fuel filter and spark plugs have been recently changed.

Don't bother disconnecting your battery; it's a waste of time. Trying to reset the computer when you have an issue does not address the issue. Also, disconnecting the battery in a '98 will not clear out any codes, so the light is still going to be on.

Have a scan done to determine which codes are being stored in the computer. It could be as simple as a tune-up or as serious as a transmission. The codes, like tx said, will point you in the right direction.