Why would my 1999 Montero sport cut off when I let off the gas?

Check air filter and have throttle body cleaned replace fuel filter if have not done so in a while add fuel injector cleaner to gas tank.

Thank you so much the air filter and throttle body cleaning fixed the problem just waiting to see when service engine light going to go off

You are welcome. Do you think it's worth a best answer check.

I spoke too soon it started again :( I've changed air filter cleaned throttle body new air filter and put gas treatment

I meant to say new fuel filter too

There is two things I would like you to do first go to a parts store like auto zone and have them read your codes from the check engine light being on they read them for free and since you put in fuel injector cleaner take vehicle out on road and hit your passing gear a few times this well help clean the fuel injectors and remove any gum and carbon build up. Be careful no speeding ticket. You do not have to do them necessarily in that order.

Do the fuel filter first.

Already put new fuel filter I put that first

Oh ok see you just forget to mention it the first time.

Yea I going to get fuel injector cleaner and hit the interstate see what happens

Ended up having to take to shop :(

Looks like I'm having the same problem, what did the shop say was the issue?