If you suspect a cylinder, one way to isolate it would be to do a cylinder balance test. You can do this by running the Key On Engine Running test and when it is complete you just tap the accelerator a little. The RPMs should rise for a while and then at the end it will start flashing the cylinders that were weak. If it flashes a 9 they are all okay. It will flash each code twice.
You can do these tests without a code reader. All you need is a jumper wire. Jumper it according to the photo below:
Make sure the engine is warm. Install the jumper. Hop in and turn the ignition key to the on position. It will run the Key On Engine Off test at this point. Each code will flash twice. The first set are the quick test codes which will be followed by a long pause and single flash, long pause and then the continuous codes will start flashing. I think your 92 will have 3-digit codes so keep that in mind.
After the KOEO test, start the car and it will run the KOER test. Write down the codes from that, too. When it's done, do the cyl balance test.
------------------
351W 89 Mustang GT Convertible
[This message has been edited by jimberg (edited 10-11-2001).]