1991 Chevrolet Silverado • 225,000 miles

I have a 91 Chevy k1500 4x4 p/u with a idle issue. Truck starts and runs fine at first. Starts up, high idle comes on and than goes down. After driving for a while (approx 30 miles) when I shut off the truck and re-start it the idle is really fast. I have to fight the engine with the brakes to get it stopped. The idle never drops back down untill the engine has sat for a while and cooled off. When this happens the truck will go approx. 15 - 20 Mph and not slow down unless I use the brakes to stop
It. Also this weekend a new issue started where the brakes have no real pressure and I can push the pedal to the floor. Don't know if these are related or not? I've read so many diffrent things and don't want to just throw parts at it and get no where. Thanks, -Brandon

Remember I said to check the hose leaing to the pmap sensor to make sure it has no holes or soft? That's on the firewall that is what I suspected but wasn't sure but it hink you saidhoses were ok, well pull it off map and see if you ae getting vacuum through it. If you are replace it. Check wiring at tps and see ifyou are getting voltage through any of the wires. And the vss may be why your speedo isn't working or the wiring is bad. It all relates to each other when vehicle is running and warm.

Dec 7, 2012.
Ok. So to make sure I am doing this correct. I am going to pull the vacumm line off the map sensor and check for vaccum. If I have vaccum replace the map sensor? Also check the tps wires for voltage with a multi meter. If I do have voltage what would be next? R/R the tps? I have replaced the vss and the inst. Cluster. Broken wire possibly? With the miles on the truck and the electrical problems I am having do you think it is possible the ECM is going out? Thanks for the help on this stuff I will definitely be donating some more money to the website.

Follow the charts i'm sending. And look at th pics so you can probel the right places.

Dec 7, 2012.
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