I'm having the same problem and my local mechanic tried several different tests to try and find the problem, but with no luck. After he had my car for 3 weeks, he finally returned it with no fix.
In my case, it's a 4-Runner. It cranks fine, but the acceleration is horrible. Doesn't matter if it is between 10-20 or 70-80, it's very slow.
I'll keep checking back to see if anyone responded.
As it becomes contaminated, it tends to under report the volume of air coming into the engine requiring the ECU to correct excessively to avoid running lean...
We took ours to the dealer a year ago and they replaced the mass air flow sensor and it was fixed. Expensive yes, but it shut the wife up even though I told her her that's what it was and I could order a replacement from dallas toyota and do it myself for less. Oh well...$260 for it but it only took them 45 minutes. Mine would have never gone to the dealer (tacoma). I got a great dealer here, you can go in there and ask them and they will tell you what the most likely thing that is causing the code. Her 4runner was a 99 with the 3.4 v-6. Cleaning may work also. The gas mileage went to hell when that code came up too.