o1 blazer 4.3L high engine idle
 

to start I had a P0200 code and a P0304 code it would not run without bogging down and I could same gas at times.we found the wiring harness was melted fixed that. I replaced the fuel injectors, fuel pressure regulator, cleaned the throttle body,and put new upper intake gaskets. runs alot better. no gas smell and only bogs every once in awhile. Now I have a P0507 code I have replaced the iac cleaned where the iac fits into the throttle body but i still have the code and blazer wants to drive its self now. it idle at 920 to 980 in park and 800 in drive with foot on brake but when i take my foot off it takes a second or two but it will kick up to 1500-1800 rpms with out my foot on the gas when i push the brake its like your driving with both feet but it with come down to about 800 rpms. when put a scanner to it and its pass every test you can put it to. so i put a new tps just to see and still have the same issues and the same code p0507 please help i am out of ideas.

What wiring harness?

after it comes out of the pcm it was sitting on the exhauts manifold and burnt half the wires

I think you have a mass air flow sensor on that on my 95 I do not. Unplug it and see how it runs. Should be somewhere before the throttle body.

it quickly idles down then right backup again right were it was.

Think yea might want to check real good for any vac leaks and on the BF home page google box try brake booster symptoms.

i have replaced all the vacuum lines i can find i also closed the brake line hose no change still what to drive her self.

Its possible the IAC was damaged during cleaning. Did you mess with the screw at all? Did you try to unplug the MAF to see if it helps?

i replaced the iac after i clean the throttle body. no i have not messed with the screws . when i unplug the map it idles down and right back up again. is that good or bad?

i have also sprayed carb cleaner around the upper intake and throttle body can find a leak there. i dont know where else to look or what else to do