I have an 86 svo gt 4 banger thats been converted to a 5.0 five speed and is completly customized inside and out. For about two months now it's been acting up. My idle is set at 1500 rpms and when i drive it for about ten minutes it'll idle way up just a little over 3000, but if i shut my car off and start it again it'll go back to 1500 rpms for about two minutes and it'll go right back to 3000 rpms. If i drive it for awhile like that it seems to get a little better and will eventually drop down to 2000 rpms, but thats still to high. I was wondering if anyone might be able to give me some advice on what to do about that. I mean, come on that tends to suck a lot of gas. You know what i mean? Oh it's full enjected also.

 

I have a 5.0 in my car. I think it's an early 90's 5.0. My prolbem is whenever i tap the gas real fast It'll backfire. It kinda lags throttle responce also. Whenever i shift it'll do it too. Say if i put the gas to the floor in any gear (because it does it every gear) and then shift and put right back to the floor, like if i'm racing, it'll backfire everytime. Can one or two of you guy's help me out with this. It would really help us. Thanx

 

Sounds like your idle control valve. You need to clean it or just replace it...

 

i just had the same prob with my 89 5.0,i went the rout of idle air valve & even the tps,but in the end it was a nasty mass air elements. it was acting the same as you describe. it was driven me nuts. look at the elements(lil coils) if they are intact then try cleaning them with rubbing alcohol not carb cleaner.they should be a normal metal color not black as i found out.
providing yours is fuel infected not carbed,
idle valve i foud out wont do that,it will give a ****ty idle or a lil low,then high,but not that high.good luck

 

ok,crappy idle then,i forgot about the naughty language dealy