How to set the timing?

I have a rebuilt Toyota 22re engine fuel injected . it starts fine, it idles fine, I have the timing set at 5 degrees for TDC . The thing is that in driving the truck, it is totally gutless, and when I put a timing light on it, and rev. the engine, the timing retards before it advances. This vehicle has no pod on the side of the distributor, So I assume it is electronically spark advanced. Is the spark advance and retardation run by the computer/brains, ? If not what controls it ? What could be the cause ? Or is it normal for this vehicle to retard right before it advances on timing mark ? Thank you for your time.