i was driving my mustang put about 400 miles in a day on it. then i stopped at a red light and noticed it was idling real rough jumping a little when i acceled it had not much power it was kinda like bwa bwa bwa then it would go fine once i was over like 25 mph mechaninic says 1 and 3 misfiring that engine may be junk also may be fuel injectors has anyone ever heard ofanything like that or any ideas what else it could be please help
I would not talk to a mechanic anymore who is ready to condemn an engine because of a misfire. That's ridiculous.
Just like it was mentioned above, a tune up will clear it up. Worst case scenario you may need an ignition coil.
You can just start with spark plugs but tune ups have to be done regularly. Can't avoid it. If you want to do things correctly, pick these items up and get it done:
Copper or Platinum spark plugs (Motorcraft,Autolite,NGK), Spark plug wires, Two cans of Seafoam- One can into gas tank & the other to clean upper intake manifold. Do not
skip out on the upper intake cleaning. Fuel filter, Check the pcv valve or replace it. Install a quality air filter(K&N filter will pay for its self quick driving 400 miles a day)
If you have to replace the ignition coil, I recomend an OEM replacement or American Muscle has the Screamin Demon coil for $80.00 I believe. Those two appear to be bullet proof. I have the Screamin Demon and it performs flawless.
Have you tried switching plug wires to determine if ones bad on cylinder 1 or 3 yet? Its probably best to replace them. If your putting that many miles on the car then this type of preventive maintenance should be done every couple of months.