99 s70 GLT 2.4L non-turbo
The car starts just fine then the engine revs a little and then sounds like its gonna die but when put in drive i can put the peddle to the floor and i will not gain any speed?? any suggestions would that be an issue of using mid-grade gas as compared to premium??

 

How long have you owned the car? Do you have a CEL? Has this problem been getting worse? Not enough information for anyone to help you.

These cars run GREAT on any grade gas.

 

I always run 87 octane in my normally aspirated 1998 S70, no problems.

 

Only had the car for about a month, CEL? just got it registered a week ago and started drivein it, it ran fine sometimes then some times would have that problem, but now it seems to have gotten worse.
Im new to volvos.

 

I use 89 octane and it seems to run the car fine...91 would be better but who can afford 3 bucks a gallon!!!

 

I run 93 all the time in all of my cars. I figured that I get better gas milage with it so that makes up the difference.

As for the NO POWER problem, CEL = Check Engine Light. It kinda sounds like your car may be in the "Limp Home" mode. If that's the case, you will have a cel. Until you get that checked and cleared the car will likely stay in Limp Home. If you do have a cel, you can go to AutoZone, O'Reiley's, etc. to have the codes pulled for free. Then post them back here.

 

P0036 was the code, downline O2 censor is what autozone told me.

 

correction p0036 (code) Heater Control Circuit (Bank 1 Sensor 2) from which i understand is the rear o2 sensor? and if so, where abouts is that located?

 

I'm not sure about the code but the rear o2 sensor is just behind the catty on the exhaust. I have not heard of an o2 sensor effecting power though. You may want to wait for a pro to answer that, like tech, carrot, etc.

I did a search and found this link: https://volvoforums.com/forum/volvo-s70-33/i-need-help-guys-28702/

 

Replaced the O2 sensor and it ran good for 4 starts and no CEL then CEL came back on with the ETS light and back to the same problem, when it ran w/o the CEL on it runs perfect, but shut it off and it comes back on. also with the ETS light. i found this link for a recall, take a look at it and let me know if you think this could be the problem.
http://home.comcast.net/~donwillson/VEXED_won.html

 

My 99 Volvo s70 has no power when cold but when warms up runs great. Any ideas?