I need some help figuring out why my 98 Disco is idling at about 2000 rpms. It started after I had a slipped sleeve and had to replace the engine with an engine from a 96 Disco with about 90k miles on it. Everything else seems to run fine, just the truck is always lurching forward because of the high idle. Occasionally it will go back to normal, but then after starting it again a couple of times the problem comes right back. I took the TPS sensor out of the old engine to see if that would fix it, but no such luck. I have heard that perhaps the gasket on the TPS could be bad and causing the problem and I will be trying to swap that out today. Are there any other suggestions?

 

Did you replace the short or long block, have you checked for a vacuum leak?

 

We used a long block, but the mechanic had to pull of the fuel injection system because it didn't match what was in the truck so the system from the old engine was used.Supposedly my mechanic checked for vacuum leaks. Where might I look for a leak?