My car starts then sputters and quits like it loses all compression when it gets close to fifty. Or it will run fine for awhile then when I have to slow down and speed up again it will lose power and drop speed, then quit. Could this be a vacuum problem? If so, where are the vacuum hoses and what do they look like? I don't know anything about engines.

SOURCE: Van Sputters And Loses All Power When I Accelerate

Internal combustion engines requires 3 things... fuel, air, and spark. You do not have enough of one or more of these. If the wires and plugs are old, change them.  Air filter, same thing.  Fuel filter can also clog up with stuff after awhile. When you take a look at the air filter check where the air comes from.  It is possible a little critter has built a home and blocked the air flow (rare, but, it has happened).

SOURCE: a/c comes out of front defroster. I also found a vacuum hose lose near the front firewall and I cant find out where it goes.

vacuum hose over top of engine attaches to vacuum outlet port on intake manifold by pcv outlet port. this line is vacuum supply to heater controls.

SOURCE: Engine loses power and dies while on the highway

could be a dirty fuel filter

SOURCE: I have a p2138 code

There is a GM Technical Service Bulletin (TSB) on this issue, below is a summary;

#07-06-04-019A: Intermittent MIL/SES, DTC P2138 with Reduced Engine Power (Repair Instrument Panel (IP) to Body Harness Connector)

Models: 2005-2008 GM Passenger Cars and Light Duty Trucks (Including Saturn)
2005-2008 HUMMER H2
2006-2008 HUMMER H3
2005-2008 Saab 9-7X

Condition

Some customers may comment on an intermittent MIL/SES light Illuminated with a message center or an indicator that displays Reduced Engine Power. DTC P2138 - Accelerator Pedal Position (APP) Sensor 1-2 Correlation may be set. The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than a brief period. Refer to DTC P2138 in SI for further diagnostics.

Cause

On some vehicles, the IP to body harness connector, which carries the APP signal to the ECM/PCM, is located in the left hand kick panel area or inside the IP. Water intrusion into these areas could cause an electrical short in the APP circuits setting a P2138 code.

Correction

Note: Make sure that no add-on/aftermarket equipment is electrically connected to the APP signals or to the other ECM/PCM five volt reference or return lines. These can generate false P2138 and/or other ETC System DTCs. If there are other engine DTCs besides P2138, such as MAP sensor faults (i.e. P0107, P0108), resolve these first before attempting to diagnose P2138 DTCs.

Important: Refer to DTC P2138 in SI to confirm that the ETC pedal is operating correctly.

Locate the IP to body harness connector, which may be located in and around the left hand kick panel area or inside the IP. Check to see if there is a water leak into the area and repair as necessary. Use a water hose to determine the source of a water leak and effectiveness of repair. Some examples of potential water leaks are: A-pillar seals, sunroof drain lines (if so equipped) and windshield/cowl sealing. Finally, repair or replace the IP to body harness connector, making sure no corrosion or debris is left on or between the terminals.

SOURCE: 1995 chevy 350 motor, MAP vacuum hose when i put

Is there a check engine light on? Were you able to pull a trouble code from the computer. At this point, it seems like the MAP sensor is at fault, but I want to be sure there are no other codes.