my lo3 is acting iwerd. for one it idles really high. in the morning when its cold it idles at like 2250 and when it warms up it idles at like 1250. i get ses light fairly often and i ran it on a scanner and it said it was the temp signal. i replaced my temp sensor and it got better but it still get the light every now and then so i think that might be the plug. i get bad gas mileage. like 13 miles to the gallon, the only mods i have is shorty headers, no cat, and a moroso spiral flow muffler, and i put an open element on it. i also have a 160 degree thermostat and a hypertech fan switch. the mileage was bad before the t-stat and the switch. i did a full tune up replaced o2 cleaned out my egr and i still get bad mileage. any ideas?

A high idle is a sign of a vacuum leak. Have you checked all the line comming out of the TBI along with the base of the TBI unit itself?

i will check it tomarrow. also everynow and then when i'm stopped all of a sudden the engine will rev up and try to move the car like it will just rev up t oabout 3 grand all on its own wit hmy foot off the gas and on the brake and then it will drop and jump back up and either stall and die or return to idle normally.

I ran into a problem similar to the one that you are having with yours when I did my engine swap. I also assumed a vaccum leak as shifty has indicated. However I found my problem to be alot more expensive.

My ECM went bad, and it did the exact same thing. The car ran in "Limp Home Mode" idling very high and triggering misc SES light codes. After a few hundred $$ and alot of testing, finally I came upon the ecm. Luckily, I have spent way too much $$ at the local auto parts store and they let me "borrow" an ecm, and sure enough, that's what it was! I'm not saying that this is your problem but just something to think about if nothing else works

check your timing.