Car won't go up hills!!!
 

I have a 92 940. I've changed the air filter, spark plugs and wires. Last year the fuel pump and relay were changed because it would just stop running and would start up in a few minutes. This year, when i start up in the morning it stalls or will run for a few until I put it in gear press on the gas then it stalls. I have to let it run for a while before it can go (this is in the summer). When i press on the gas the car hesitates pretty badly. I can drive it, but it has really poor acceleration. It sometimes won't get pass 25mph. Going up hills is the worst. I could be going at a good speed, but when I hit a hill the power drops and speed drops back down to 25mph. We changed the TPS which helped alittle, also had the folks at Midas look at it for a possible exhaust issue, they said they found a leak and sealed it. I definitely feel more power, but it still hesitates and can't get up hills. Can some one help me please! Looking at the air mass sensor as the next step. What about temperature gauge? O2 sensor? What do you think?

I'm surprised Midas didn't sell you a new catalytic converter. They're good about that! And, really, that sounds like it might be your issue. A simple, often effective test is to get behind the car by the tail pipe and have someone who doesn't have a vendetta with you rev the engine. If you hold your hand near the exhaust, the pressure coming out should be much greater as they rev the motor. If it seems anemic or you're not sure, try another car that is running right. Often, a bad cat will actually blow out particles when revved as the insert is broken and disintegrating.
The simplest test of the amm is to disconnect it while idling. The car should run significantly more ragged. If it does...save your money. If it doesn't, look at the contacts in the plug that goes onto the amm. Often the copper contacts get corroded or bent. A clogged air filter can also stop up a motor. While in the air box, notice the little flapper that goes to the preheat tube on the exhaust manifold. It is thermostatically controlled. If it sticks in the open position, it will allow heated air into your amm and fry it. If you suspect the it has failed, it's quite simple and accepted to drill a small hole and zip tie the flap shut to prevent it from happening anymore. The only down side is the car will take 60-90 seconds longer to warm up in the dead of winter. If you do not know the history of the O2 sensor, by all means replace it. As the only sensor that gives the ecu input on the actual fuel mixture, it is imperative that it works properly...yet is often overlooked.