More on my problem with the TBI on my 1993 C1500 350 automatic. I have replaced the TPS, the following sensors...Map, O2 & coolant temp, Injectors, idle air control, Electronic spark control, fuel pressure regulator & fuel filter. This started as a simple injector replacement as it was hard to start & the vehicle has done 350,000km. After replacing just the injectors the engine was running rough & would cough as though in a lean condition so I replaced everything associated with the TBI with no better result. It starts first hit of the key idles perfectly, revs beautifully stationary but as soon as it is underload ie driving it the performance is terrible. Rough running, coughs if you try to accelerate quickly. So it is not a pleasure to drive. I live in Western Australia so all parts have to come from USA at considerable expense.

My question is if I replace the stock TBI with say a Holley unit to just run the fuel system would leaving the existing ECM to run everything else work? Any advice would be very welcome.