My 2002 hyundai accent 1.6 wont go above 25 miles an hour. idles high at 1500 - 2000 in park. drives normal until 25 and wont gaain speed til i drive another mile and half down road, then jumps tp 3200 rpm and goes to 40 mph. but thats it. no further speed even when i push gas pedal all the way, i was told the map sensor could cause this?

SOURCE: Acceleration - cannot get above 40 miles per hr.

If the engine revs up while in drive and running at 40mph, your transmission is probably slipping. Try checking your transmission fluid level. If it is OK, I would get it by a garage to have them look at it to cofirm.

SOURCE: High rev when starting hyundai atos

Check the vacuum hoses, but sounds like the IAC or even the o2 sensors. The computer will pick up on the o2 sensors but not the IAC..Go to your local ADVANCE store and they will check on computer for free :)

SOURCE: vehicle hakes when driving 45 to 50 miles per hour

Check wheel balance,
check steering linkages for loosness - such as tie rod ends, steering rack linkages etc,
check driveline for worn/loose joints and bearings.

SOURCE: bogs down on acceleration

buy 2 fuel filters. buy can of SEAFOAM at parts store. use 1 f filter to replace old one(you'll probably see old looking gas, with an odor).Pour SEAFOAM into tank. fill up with PREMIUM gas. after about 100 miles change out fuel filter 1 last time..add SEAFOAM every 3-5000 miles and you should be fine. the ethanol in the gas turns to goop and adds water to your fuel, and puts carbon on your valves and through out your emission and fuel system. The ethanol will be alright as long as you follow these instructions. and the SEAFOAM will keep you from having line freeze up in the cold months ahead, and will give you better gas mileage. good luck.

Testimonial: "OK I'll try it."

SOURCE: starts/stalls won't run until pedal tapped, 2

Check your IAC motor (Idle Air Control) It could be sticking open.
Ps. Might be called Idle Speed Control motor it depends on the make and i forget what chevy calls theres.