Fuel Injector or Transmission Problems?

Car: 3.1
Year: 1999
Miles: 137,000

After feeling lag in acceleration, I had my transmission flushed (it was bad) and that didn't help, so I replaced the fuel filter and PVC valve. Still felt lag on freeway.
It runs fine until i get to the 30-45MPH, and that's where the problmes lie. Lagging acceleration. I thought it might be the transmission, but I don't think that it is. I have been advised by my neighbor that it might be the fuel injectors.
The check engine light comes on. It flashes then remains on.
I want to get as much info before I take it to a shop. I hate being a girl taking my car to the shop..ugh..

If you have an Advance Auto or Auto Zone in your area, they will scan your car for free. Get the codes and post them here. It will help immensely in helping you diagnose your problem.

Yeah, there's about a dozen different ways you could go with that, but getting the codes should at least give some insight, if not point you directly to the cause.

It's better than having a symptom with no check engine light, where the self-diagnostics are no help...