91 Toyota 4x4 3.0 liter idle problems

Hello. I hope someone can help me. I just purchased a 1991 Toyota ext. cab 4x4 pickup with the 3.0 liter engine. Also it is a 5 speed. The problem is at cold start in the morning it idles at about 1500 rpm. It will eventually drop to around 900 rpm, but only after it is good and warmed up after several miles of driving. Also the idle is choppy all the time. Before I bought the truck the head gaskets were replaced. It looks like they did an ok job. All vacuum lines are correct. When I remove the oil fill cap the rpm drops about 100-200 rpm. I have been told this is normal because its causing a vacuum leak. I have also been told this is a possible throttle position sensor problem or dirty or stuck injectors or pcv valve. This is my first toyota so any help would be appreciated. Thankyou very much for looking, Brandon

I would say it's a dirty throttle body.

To clean the throttle body remove the air intake hose and examine the intake and throttle body for excessive carbon build up if found then buy a can of throttle body cleaner labeled "safe on oxygen sensors,TPS's and catalytic converters" do not use carb cleaner make sure your engine is fully warmed up prior to using as when the throttle body is hot it dissolves the carbon easily and quickly.The labels usually specify to park the vehicle at ground level (0 degrees,no inclination) and have the engine running but I disagree I instead park the vehicle on a hill facing down and shut the engine off and hold a rag below the lip of the throttle body and poor the stuff and use a tooth brush.

Sidney® ™
Repairs tv's,vcr's,home/car audio out of my home
E-mail:[email protected]
Dartmouth,Nova Scotia
Canada
1985 Toyota 4-Runner,solid front straight axle,factory cruise control,sunroof,22R-E,W56,RN60LV-MSEK,rusted rear step/towing chrome bumper with 246 000 KM