To elaborate upon what Charlie posted... The disk type (3.4 Camaro) injectors have different operating characteristics from the pintle type (Fiero) injectors.
At higher RPMs, the disk type injectors are just fine, but the Fiero ECM can't control them reliably at low RPM.
Ron S posted a fairly detailed explanation, a while back, of what needed to be done to the programming, in order to make them work with a Fiero ECM, but it was (if I remember correctly) a set of parameters that I've never messed with. Seemed fairly complex.
Also... it's a somewhat popular misconception that 88s all came with disk type injectors. I have heard that, as well.
That may have been true for a handful of cars, but not most. Every 88 that I've ever been into had the same injectors as the earlier cars. Pintle type.
To further add to the confusion, some of the 88 fuel injector harnesses had square plugs, although most of them had the same flat plug as the earlier cars. I wondered if there might be a correlation between the square-plug harness and the disk type injectors, but there was none to be found. They both appear to be random occurrences. (There was even speculation that GM ran out of pintle type injectors, late in production, and just threw in whatever was handy. THAT wouldn't surprise me a bit. Of course there was probably a good chance that they wouldn't idle correctly. But by then it was a customer/dealer problem.)