Hi, The Toyota Estima 3CT-E motor that I have has a brand new cylinder head and Head gasket fitted but still getting water into #3 & #4 Cylinders. What can I check next or what do you thing is the problem. Appreciate your advise, Thank you

There are several likely causes, none very rosy: 1) head is warped (was it surfaced and/or straightened in conjunction with the new head gasket?). 2) gasket damaged during installation. 3) head is cracked. 4) block is warped and/or cracked.
If you are committed to the car I'd recommend finding a re-manufactured head from a quality supplier and have it professionally installed. That covers 1 -3. #4 is very difficult to access without removing the engine from the car and taking it apart and having it magnafluxed. The only sure thing is a complete engine with a warranty. Cost of the reman engine is probably in excess of the value of the van.
Good luck