where should i tell him to start ??

[motorman]

I have an engine problem and have not been helped by diagnosis testing at the local Chev. dealer. 1990 vin 8 engine: all 8 injectors replaced in 1991; previous owner got gas with ethanol in 2005 (I can't understand why this was a problem), he had engine problems took to Chev. dealer and they replaced 3 injectors, replaced the fuel filter and cleaned the system. I purchased it I replaced the fuel pump, sock and sender (fuel level sender was bad) ; engine idles a little rough, surges slightly at 1200 to 1500 rpm, and the entire engine runs rough above 1500 rpm (no backfires)very noticeable 1500 to 3000 rpm; 1 ignition wire was bad and all were replaced along with cap, rotor & plugs. TPS sensor and oxygen sensor were replaced. Can you suggest someone who can diagnose this and help me? Preferably in the North Hill area.
I would appreciate any help you you can give me. THANKS

[c4c5specialist]

HI there,
Start with fuel injector resistance, then fuel pressure, then ask what kind of parts were used.
IF they were NOT ACDelco, thats where you start from.
Allthebest, c4c5