Salam friends.

I own a toyota townace 2009 s402m van which has a 1.5 3sz-ve engine.. bought it unregistered from peshawar. used it few kilometers locally then on my way to abbottabad, it gave me a check engine light.during check engine light the car sort of runs into limp mode.. i.e. it takes start from first gear then with the sound and reduced pick i assume it shifts directly to third gear and the speed it limited to 80 kmh with max engine rpm. i bought a code reader, it showed two codes p0011 and p0016. Now p0011 automatically disappeared after changing the oil and filter to Toyota genuine.
Here is what happens:
Now the fault p0016 appears intermittently. not every time.
when i start the car in morning and leave it for a 15 to 20 minute warm up. and start travelling, it some times gives the same check engine light. so i park the car turn off the engine.give it a break for 1-2 minutes. after this short break the car starts fine and runs perfect for that trip session.
This problem in intermittent. so where you guys think is the exact problem. dtc codes says maybe chain stretched or skipped a tooth or faulty chain tensioner. and if it is necessary to change the timing chain. please tell me what other engines used in local assembled Toyota use the same chain because 3sz-ve engine spares are not available with Toyota Pakistan.
As the car is re conditionedand the engine is changed because the number on engine differs from that of the chassis plate. hence cannot assume the life of the swapped engine.
Your comments and suggestions will be of immense help to me thanx.