Car idles different and temp gauge doesn't move when car is warm. I have heat. on 1995 Buick Riviera

It seems to not shift properly. Normally when stopped at a light RPMs about 700. Lately its been above 1000 RPMs. I am getting horrible gas mileage. Any suggestions to figure out how to fix the problem appreciated.

by in Inkster, MI on February 20, 2014
2 answers 1 comment
ANSWER by on February 20, 2014
Gotta see if any codes in computer..
ANSWER by on February 21, 2014
poss vac leak and temp sending unit. does the car over heat on you?
COMMENT by on February 21, 2014
It has turned off while driving once. I pulled over and waited a minute and it started up. Its hard to start if I go in the store for a couple minutes.I don't believe it was overheated though. I felt the hoses and it felt like there was pressure. How would I know if it was the temp sending unit?