Idles rough during long periods of driving while stopped.

Depends on what you mean by rough. Could be a cylinder misfire.They sometimes are not noticed as engine speed increases during driving or under light load as when idling in neutral but at idle under load as when stopped at a light in drive became noticable.
Could also be running rich. The causes of either are too numurous to list.Consult a good mechanic who can actually see and hear the problem to put you on the right track.

Try filling it with a top grade premium gas.

check for loose/ missing vacuum lines on the engine . Easy enough when replacing an engine.

I had a similar experience. Finally the car started overheating. Turned out the thermostat went bad and the radiator blew a leak. Had those replaced. Runs great.

Hello. Welcome to FixYa. Please allow me to assist you.

What you have is this: Disconnecting the battery caused your car's computer to lose its 'base idle' parameters. This info is kept in the computer, but, removing power to the computer allows the info to be erased, so to speak.

This is, unfortunatly, a normal condition, and, easily rectified.

What you need to do: Get in the car, start it up, and drive it; simulating stop/start city traffic, and then take it out on the highway, hit passing gear a few times, pull off, and let it idle 30 seconds and repeat highway speed, and passing gear a few more times, then simulate city traffic again. You might need to apply a slight bit of gas during the idle periods of the drive. If you do it right, you can reset the base idle parameter under10 minutes.

If you have any questions, please feel free to get back to me via reposting.

Thanks for choosing FixYa for assistance today.

idle air control is bad

hi barry i have the same problem did you ever fix yours ?

adjust the TPS, throttle position sensor.

First though, disconnect battery for 1/2 hour. Restart engine and drive for 15 miles while computer relearns changes you made. Will run rough for this period.

Check the hose between the inletmanifold and the pipe to the brakeservo it normally gets old and a crack in so the engine sucks false air on cylinder 4, causing engine to run rough or uneven.

Try checking your Spark plugs (they MUST be the right type, clean, and properly adjusted: and try adjusting your timing. Either or both of these could cause this type of problem Hope it helps. If so, don't forget to rate the answer, will you?