Mighty max 1995 2.5 5Vel, i start the engine and after 10-15 minutes i am running and suddenly the aceleration down and after some seconds acelerate again but only to 45 mph if i try to acelerate more, the aceleration is down again

Hello, This sounds like an ignition, fuel or exhaust issue. A clogged catalytic converter, especially if the element has broken apart, can cause this, and you would be listening for a rattling sound. Next, test the distributor vacuum advance canister. If it has a leak, you get this issue. Next, if the distributor rotor, cap and wires are old, worn, and especially if the have not been maintained according to manufacturer suggested service intervals, it may be time to change them. Do you notice any change when the fuel tank is full v empty?