Heres a good one for youins', I usually find what info I need without posting. Its great to have some really good techs out there willing to help out the needy. I have been in the field for many years myself.
We have a 2000 Honda Accord 2.3L would not go over 65mph, poor idle too.
Yeah I know what yur thinkin so was I, and went ahead and replaced what ever sensor failed the diagnostics. Ok no codes now Idle is good. All wiring and grounds were checked and/or cleaned. Still bogs down at 3,000 rpm 2nd or 3rd gear. After looking at the scanner again I'm getting a reverse Map sensor reading. When vacuum is high scanner says its low, WOT inHG is high???. Tests @ the sensor are in spec. Anyone see this before?
If not got any ideas, besides replacing the PCM.

 

How are you testing vacuum?
With a gauge installed and watching vacuum through the scanner via the MAP sensor readings? If so then I would suspect the MAP is faulty.

 

Checked it 3 ways: Vacuum gauge at the manifold port behind the map. Scanner reading in digital and graph mode, Voltmeter backprobed at the map reads according to manual, Low voltage high vacuum, high volts low vacuum.
Scanner reads the opposite. PCM apperars to reading the signal exactly opposite. A bad PCM circuit? But it reads map signal. ??????

 

Is it safe to assume it didn't just start doing this. Any engine work done lately ? Any wire work done ? Did you swap the wires yourself somehow ? Can really only be any of those.

 

So your scanner shows in/Hg? And it is opposite of the mechanical gauge?
What actual in/Hg numbers are you seeing on both scanner and gauge. What manual are you referencing, Haynes/Chiltons often has MAP/DPS sensor readings listed incorrectly.
A MAP sensor cannot just 'flip' its readings. Are the reference, signal and ground wires in the correct terminals?

The only other thing that could cause a build up of positive pressure in the intake would be reversion either through a damaged intake valve, or restricted exhaust. Any Bananas, Potatoes, or fresh fruit found near the rear of your car recently?

 

Thats good, banana in the tail pipe... and yes a head gasket was replaced about 300 miles ago at a shop in IL. the the car was shipped to here AZ. They did a terrible job and over charged for it. I punched out the 20% clogged converter first thing. Still bogs at 3000 rpm.
The owner of the car says it happened all the sudden pulling away from a light. The terminals are correct. I'll admit I have not worked on alot of hondas, but they are all close in operation. I needed to prove the engine was ok so heres what we did. In 3rd gear u can just hold it to the floor and it will just stay bogged @ 3000rpm. So we removed the map and plugged the hole, left it connected. Then hooked up a vacuum pump to the map. With my buddy in the pass. seat ready to pump.(hey leave it alone I rephrased it) We went on a test drive, remember computer is seeing it backwards. @ 3000 rpm WOT scanner was reading 27-29inHG. "I know strange" I managed to get it to 3rd gear WOT and its bogging 3k max until he operated the vacuum pump then the car started accelerating. Went up over 5500, whats up with that???? SMOOTHLY! I to replace the PCM with out knowing for sure. Im gonna try a diff scanner?

 

What was this fix I'm having this same issue on my prelude.