It is very possible that he was seeing 7K rpm fourth gear in the automatic if you consider the slippage that the automatic transmission has in the torque converter. If he was running into stiff wind resistance he could experience more slippage in the converter.
Think of it as power-braking, the effect you get when you hold your foot on the break and push on the gas with an ATX. It will slip up to a certain rpm and assuming nothing breaks it will continue to slip until the hp=slippage. At idle when you power brake the engine will only go up to something like 2500 rpm or so, that is partly because there is not enough power at that rpm to accelerate the motor faster against the drag of the converter.
Now picture him already around 4-5K rpm in top gear (130mph or so?) where the engine has maximum torque...the engine can then accelerate a little more while the converter begins to slip more and the car ends up not going any faster because of wind resistance. Even though the tach is showing higher engine speeds.
I know its a long explanation..
warmonger
