When I start my truck when it's on a slant like a driveway, it won't idle. I have too keep my foot on the pedal. But as soon as I get it on flat pavement, it runs fine within 30 seconds. Any ideas what's wrong?

 

i can't think of any reason why sloped ground would affect engine operation other than the oil pan and gas tank, neither of which would be affected by pressing the gas pedal. so, i don't know.

i'd go back to the basics of idle control. clean IAC well port and replace IAC motor first and reset pcm and if that doesn't fix it replace TPS next. keep the old sensors just in case it doesn't fix it and you'll have a set of spares, which is useful.