Check all belts and anything that was removed while changing the timing belt, to make sure that nothing was damaged. If everything is ok, then the timing belt may be loose.
timing belt has absolutely nothing to do with the heater, there is an idle-up solenoid that keeps the idle from decreasing when the fan is turned on(whether it is the heater or AC), check this solenoid
Check Timing First Sounds Like That Is Your Problem. If it turns out to not be the ignition timing, it could also be the camshaft timing. If your camshaft is mistimed it means that your timing chain or timing belt has slipped and must be replaced.
1998 rav4 engine wont idle and clacking noise from under timing belt cover
front of timing pulley making rumbling noise took belt off and still making the same noise.is the timing chain are is it a bearing on pulley.
Sorry, disregard this question, I didn't word it properly.
timing belt
Check all of the plug wires. Make sure they are all routed correctly, and on tight. If that is all good then perhaps the timing belt is off by a tooth or two.
Timing belt. misfiring engine
No, check idle pulleys and belt tensioner.
You do not have the correct timing set for that car.
Cam or cams not lined up with crank properly
Computer needs to re-learn the idle. Spark plugs are bad. Valves are not properly gapped. Adjust Idle Speed on Throttle body.