I recently just got my 1990 pickup 3.0 ltr 3VZE engine rebuilt. I dropped the engine back in and everything is hooked up. When i try to start it it takes a little bit for it to start. Also once it starts the RPMS surge up and down constantly and the truck sounds like its going to shut off any second. Once the truck warms up everything is fine and it all seems fine and it runs great. Also the engine light is on and i checked it and it says its the water temp. sending unit.

If anyone knows whats up please lemme know!! Need to get this truck back on the road!!

 

I had the problem with surging when the brakes were applied.There is a thread on it. If that is the case, try turning the idle speed down. If the idle speed is too high, the computer cuts the fuel when the brakes are applied. If you are surging when the brakes are not applied, then disregard this.

 

Nope wasn't that. I figured it out. The trouble starting came from the water temp sensor and the surging came from a leaky injector.