2001 Toyota Corolla Automatic: Acceleration Issues

Hey y’all, I’m hoping someone might have a little insight into a particular problem I’ve been having with my 2001 Corolla.

The car had been idling a little rough lately and I’d noticed a drop in MPG. After trying a few easy fixes I finally replaced the O2 sensor a few weeks ago. The idle has leveled out but ever since then I’ve been getting periodic hesitant-to-non-existent acceleration. Sometimes it works just fine (better than it’s been in years, actually) but then sometime it will take forever to accelerate from a stop. I’ll give it some gas and it will just roll forward at barely more than an idle for half-a-block until something kicks in and it levels out around 30mph. This doesn’t happen consistently though and I can’t see much of a pattern in when it happens or why. It seems to help a little if I ease into the gas very gently, and it is worse when I try to gun it. I was worried it might be the fuel injectors or the ignition coils but I wanted to see if anyone else had dealt with this issue before I go down that expensive route.

I appreciate any ideas you might have. Thanks!

How many miles?
How long since the last trans service?
I will assume the check engine light is on?
Please post the codes

You might have a dirty throttle body or a dirty mass airflow sensor

120K miles
I’ve had the car going on 4 years and haven’t had the trans serviced in that time.
The check engine light was on (it had be coming on fairly often for “random misfires” earlier, and I’ve recently replaced all the plugs), but I’m not sure what the code is this time. I dropped it off at the shop and my guy is going to take a look at it in the morning. I’ll try to get that exact info when I talk to him.