OK, that would help, but knowing it is getting past 60 before having troubles says to me off the top of my head that the problem is likely the IMRC and the butterflies. The engine tends to get choked for air at about 65-70 or so if the butterflies are not opening, and the common cause is that the IMRC has either broken its actuator cable or one of the little plastic gears inside it have died.
The simple and common solution is to simply wire the butterflies open so they are never closed and the IMRC no longer does anything. It turns out that, from a performance standpoint, it was not really doing anything any way, other than changing the sound of the engine as it went to higher RPMs and the butterflies went from closed to open. Basically, you find the cable coming out of the IMRC box, trace it back to the connector to the butterfly shaft actuator, and pull the shaft to full open (toward the front of the car, IIRC), and then use a very large and strong zip tie to hold it in that position. After doing that, see if your acceleration at higher speeds problem is gone. If the butterflies are crudded up, it may take working that actuator back and forth a bit to be able to get it to full open extension before you wire it there. If that is so, you might one day want to open up the intake to clean all of it out for better smooth air flow.
pax, smn
