mazdasix

Hi, I recently bought a 1989 rx7 convertible, it has 71,000 miles on it. Ok, well the car starts up and idles great, will idle all day long. Anyhow what happens is I begin to drive it and after about like a mile or so the check engine light comes on and at the same time the car acts as if it's out of gas (the more throttle I give it, the more it wants to stall), but will still idle fine during this time. However if I push the clutch in and shut off the motor and start the car back up again, it runs fine again, for a mile or so..............over and over again. The basic stuff has been done, plugs, wires, fuel filter etc etc. and I should note, the car came factory with an automatic tranny, but was switched over to a manual, this was done before the owner I bought it off of purchased it and it ran great for him for an entire summer, then he put it away for the winter, and when he got it out, this happened to him. He had taken it to the Mazda dealer with not much help, they were telling him they couldn't run their computer on it since the tranny had been switched? Does this sound correct? Cause apparently the computer was also changed with the tranny to the manual version. Anyhow, was just wondering if I'd still be able to pull codes via the "paperclip the plug and watch the check engine light method" or not, or if any of you experienced seven owners have encountered this problem before, thanks in advance.............John