This is how you remove the front bumpers from 1990-2000 model Toyota taragos/Previas
First if your tarago/previa has a bull bar it has to be removed, before you can remove the front bumper.
There are 6 X 18 mm bolts secured to the bull bar brackets, remove the 3 x 18mm on the left and 3 x 18mm on the left and place the bull bar in a secure area to reattach later, don't be surprised if its full of rust it needs to be sand blasted, rust treated and repainted.
The next step is to remove the bull bar brackets to do this you must remove the grille to access the 4 x 18mm bolts on the inside of the grille 2 x 18mm on the left and 2 x 18mm on the right.
Open the bonnet of your tarago/previa there is a screw at the top of the center of the grille that has to be removed and placed in a container to reassemble later.
The next step is a bit tricky but with persistence and practice you will get better, the grille has four plastic clips that hold the grill in place.
Now listen carefully, you cant just pull on the grille firmly and hope that strength alone will pop the grille, these clips are designed to open when the grille is pushed into place so the top and bottom of the clip have to be depressed to slide the insert out to remove the grille, but you can depress one side a time it dosent have to be both at the same time.
It just takes take and patience to do, start from the top left clip, pull the grille towards you and with a flat blade screw driver look down the grill and press the top of the clip still pulling the grille, the clip will depress but now you have to do the bottom of that clip too.
There are gaps in the grille you need a tool like a L shape pick or an interior tool shaped like a L for removing door trims, you can buy these items at $2 dollar shops, you feed the tool through the gap in the grille and place it under the bottom of the clip and when you press down it lifts up depressing the bottom of the clip while you are still pulling the grille towards you.
Once that clip is out stay on the left side and do the left bottom clip repeat the process and then do the right top clip and then the bottom right clip, when the grill is out push all the clips back into the grille so you don't loose them and place grille in a secure place until your ready to reassemble.
When you reassemble the grille you just place the grille over the insert holes and push them back into place they will automatically snap back into position and then screw the center top grill screw back in.
Now the grille is out, you will need an extension on your ratchet to reach and remove these bolts 4 X 18mm bolts, 2 on the left and 2 on the right, there is a dryer bottle on the left or right of your vehicle depending on country, so the extension needs to be reasonable long.
Once the brackets are removed place the bolts into your container, there are 4 x10mm bottom bumper bolts securing the bumper onto the reinforcement bar remove them.
Then there are 2 X 10mm upper corner bumper bolts securing the bumper to the body remove them, and then the last 2 X 10mm to be removed are at the bottom of the corner bumper secured on to a rail.
Once these 10mm bolts are removed the front bumper will slide off, place the bolts in your container and reassemble when ready.