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TBI lean surging low power

V-6 Camaros rule!
Posts: 29
Joined: 04/11
Posted: 09/21/14 06:38 AM

1990 Cadillac Brougham with the 350 TBI Chevy.  It has to be really warm to show the symptoms, like driving for a half an hour+, then it will surge under load and have low power.  

I have replaced/done the following: rebuilt the TBI unit with mods, spark plugs, cap, rotor, new exhaust, O2 sensor, fuel pump, EGR valve...  I replaced/did these things as regular maintenance and also in an attempt to fix this recurring issue.

The only code that comes up is: 44 lean O2 sensor.  It runs GREAT all the time except when it is hot and under load, like climbing a hill or overtaking, those are the only conditions when there are any symptoms.

Any suggestions?  I was thinking maybe the ignition module that drives the fuel injectors, or the injectors themselves?  It is hard to diagnose, because everything looks/works well on the scan tool and inspecting under the hood, but then after driving a while the symptoms return...  
1969 GTO resto in progress. '76 350+.060, #13 heads, 9.2:1 CR, Lunati cam, Edelbrock Performer, 750 Holley, HEI, Ram Air manifolds, 2 1/2" exhaust. TH400 trans w/shift kit and 2400 stall.  235/60/15 front, 275/60/15 rear on Rally II 15X7s.  GM 12 bolt posi with 3.73's.

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