1991 Troubleshoot

[bigspillway85]

Just picked up a '91 with 110k miles. Convert. 5 speed dark blue and immaculate. If i drive the car extra slow there are no problems. However, once i tach up over 3500 rpm under a load, the check engine light comes on, also the engine bogs down to almost no power. Once i turn off the ignition, the problem clears and the car runs fine. Until i get on it again of course. I am very new to the rx-7 and have no idea if this is a common problem or something more serious. Any help would be greatly appreciated. Looking to hold on to this car for a long time.

Thanks.