Will a loose gas cap set off the map sensor

SOURCE: Check engine light on

Check engine light has **** to do with any of what you listed. It only relates to pressures and sensors. Retorque your throttle body, check resistance on your sensors and if that doesn't work change the map sensor. They're bad on these vehicles

SOURCE: I have a 97 s-10 p/u. Check engine light stays on.

sounds like you need a shop to inject smoke in your evap system to find the leak

SOURCE: Similar Problem: Van bogs down when you step on the gas

2 simple causes for your symptoms would be water in the fuel tank (pour drygas into the tank to alleviate this problem) or a leak in the exhaust system. If both items don't apply, check for any vacuum leaks under the hood. You've isolated the problem to either vacuum leaks or a fuel problem. Hopefully, this will give you a general area to look and solve your problem. Best of luck.
Greg

SOURCE: 06 chevy impala v6 3.9 liter engine. Check engine

there is a large evaporative leak. keep away form ottozoo, they dont have the brain power to actually diagnose a light bulb., their job is to sell parts., if they sell you the wrong parts tough.Take it to a qualified repair shop that does a lot of GM work or the dealer.

SOURCE: will a loose gas cap cause the engine light to

yes its part if your emissions your car will send out code for small evap or smog leak. and just a fyi have your codes cleared on before going to emissions test cause even old codes can make you fail emissions. any auto zone can clear them