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1987 5.0 "sputtering" at idle and cruise speed

2002 Views 3 Replies 2 Participants Last post by  robzh358
I've replaced plugs, wires, ignition coil, distributor and cap. None of these replacements has fixed the problem. When I drive at a cruising speed, car becomes sluggish (almost like there's vibration) and when I hit the gas, it sputters, backfires and will return to normal after it gets some gas. It does not do this all of the time and I can usually drive it in a manner which minimizes it. If I let it idle, the car will start to run rough, almost like there is a decent cam in it and the symptoms will return when I take off. IAC has been checked and looks good. Fuel pump replaced a few months ago. TPS replaced a few months ago. Doesn't appear to be a vacuum leak. There is no MAF. Stock replaced OE parts. I seem to be in a cycle of replacing parts until I find the culprit.

When it backfires, it sounds like the problem I had when the old fuel pump was overheating and replaced, but that's not it. I doubt it's the injectors, because it just doesn't do it all of the time.

I'm a shade tree mechanic at best. I'm stumped.

Any thoughts?
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Also.... it's not giving me any codes.
Start by checking the the grounds. 9 out of ten problems are ground related. back probe all sensors to verify correct working order. and double check that the EGR valve is not Stuck open.
I have replaced just about everything electrical.... and in the process noticed the master cylinder leaking where it butts up against the brake booster. It has been replaced; after bleeding the lines twice and getting the pedal back I've driven it for 5 days. It does not spit and sputter anymore! But.... the idle surge which USED to occur prior to it sputtering is back. Would the vacuum in the brake booster cause the engine to spit and sputter? Maybe if the brake fluid got inside the vacuum line?
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