88 chevy s10 blazer 4.3 wont run right

1988 CHEVROLET S-10
400,000 MILES • 4.3L • 6 CYL • 4WD • AUTOMATIC
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BAMABOY90
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ok on my truck i changed the timing chain and gears plugs wires cap and rotor about a two years ago. ran great for about a year and a half then the problems started i have a random miss fire in park when in gear it wants to idle about 600-700 rpm so low the truck stalls out, and a strong smell of gas from exhaust. it got to the point where my truck wouldnt even start unless i had my foot on the gas i tought it was the iac valve so i unplugged it with no change. i unplugged the vacuum line that goes to the heat riser it will start up now with no gas needed but when i get off the high way turn it off then try to start it i have to give it gas again. just changed the plugs and wires cap and rotor about maybe a month ago i started it while running looked at the injectors they seem to be squirting fine no leaks i also used sea foam please help im out of ideas oh and no check engine light is on
Jul 1, 2014 at 9:42 AM
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JACOBANDNICKOLAS
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You disconnected the IAC, but did you check if it was working properly? Is this the actual miles that are on the engine?
Jul 1, 2014 at 11:28 AM
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BAMABOY90
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no not really sure how to check it
Jul 1, 2014 at 11:38 AM
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BAMABOY90
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and for the miles my speedo quit working bout 1 year ago and i have done a lot of driving the cluster says 344xxx but im sure its at or over 400000
Jul 1, 2014 at 11:40 AM
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BAMABOY90
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i also forgot to mention that when i get the gas from a stand still its got plenty of power
Jul 1, 2014 at 11:41 AM
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JACOBANDNICKOLAS
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A simple check with the IAC is to remove it, and have someone cycle the key off and on to see if the pintle at the end of the IAC moves.

If you have over 400K on this engine, you need to start by checking engine compression. variations in compression between cylinders can cause a misfire and rough idle. Additionally, you need to check the fuel pump pressure to make sure it is within the manufacturer's specs. Since you smell fuel, the pressure regulator could be bad and allowing pressure to get too high.
Jul 1, 2014 at 12:00 PM
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BAMABOY90
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would that cause the having to puch the pedel down to start it
Jul 1, 2014 at 12:07 PM
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JACOBANDNICKOLAS
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It could cause you to have to depress the gas to start it. It allows air to get to the engine when the throttle plate is closed. If it isn't working, no air can get to the engine unless you depress the throttle.

You know, it's been some time since I worked on an 88, but things are coming back to me as we talk. I remember a lot of issues with the spider injection under the intake. The fuel pressure regulator was under there too and would go bad causing issues with the injectors dumping fuel. That could also cause you to need to depress the throttle to start it and cause performance issues. Have you confirmed that the fuel pressure is within the manufacturer's specs?
Jul 1, 2014 at 12:12 PM
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BAMABOY90
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no not yet i have the tbi non vortec no spider valves here
Jul 1, 2014 at 12:18 PM
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JACOBANDNICKOLAS
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Sorry, I thought 88 had them. Check the pressure to make sure it's within spec. That could still be the issue.
Jul 1, 2014 at 12:23 PM
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BAMABOY90
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ok i will do that and get back to you thanks
Jul 1, 2014 at 12:26 PM
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JACOBANDNICKOLAS
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I'll look for your reply.

Joe
Jul 1, 2014 at 12:27 PM
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