Oil cooler
 

Ok so I want to know what is a good size oil cooler for a full flow system with a thermostat. Like how many rows.

I don't remember all the specs of mine. It was B&M about 12" x 14" x 1 or 1.5". It doesn't need much to be better than stock. FC RX-7s used one similar in size to the MKIII's but it was full flow and has an integrated thermostatic bypass. A popular junkyard grab if you're looking to do it on the cheap. It doesn't cool as quickly but unless you're making some serious power anything the stock size or larger will do. For a full flow setup you and a minimum of 1/2"NPT or -10AN for the full circuit.

Just like 300-400hp is about all I'm looking for

http://www.summitracing.com/search/B.../?autoview=SKU

I'd go 8" x 11" or larger.

Check that your PS cooler isn't going to be in the way of where you want to mount the oil cooler. If it is you can replace the pipe loop with a more efficient rail cooler and mount that wherever you like.... it doesn't nee tons of air so even the small opening beside the nose bridge of the 89+ bumper will do.

I did know it had a power steering cooler. I was think of mounting it beside or above the intercooler.

You did know, or you didn't know? There are a few different ones which were used and a couple are more obtrusive than others. I believe the one from 91'+ models was the easiest as it was mounted pretty much over the bumper the whole way; This is how I mounted my aftermarket PS cooler, but I mounted mine to the support bar and ran hose to it from the hard pipe which I cut off after it came out under the headlight. '89+ GTEs may have had a similar setup but I believe there were subtle differences (which I can no longer recall).

At any rate. Installing the cooler next to the IC is fine if you don't plan on upgrading your IC. I mounted mine in front of the A/C condenser on the passenger side where the assisting fan is located between the condenser and the radiator... So it may take advantage of the extra pull on hot days. There's less room in there to fit stuff that we usually think so think it out for a while and maybe find a local vendor so you can hold it in place to see if any of the mounting locations you're thinking of will work.