Turing over problems

When turning over the van at anytime during the day I will have to apply pressure to the gas pedal in order for the car to turn over. On the other hand if I turn it off for 5 minutes and come and start it again it will start. Is this the fuel pump? (If I get lucky I can turn it over in the morning with just one turn of the ignition)

After turning the car over my car will almost stall out on me. And the sound coming from the exhaust is thud thud thud thud thud.

I have replaced the following things due to other problems.

6 injectors, fuel filter, crank sensor, spark plugs and wires.

Can someone help.

sounds like an out of range throttle position sensor. The plastic tangs that engage the sensor with the throttle shaft get worn down, which in turn gives the ECM a false signal as to throttle position. It's mounted to the throttle body opposite the accelerator cable and attaches with 2 screws. easy fix you should be able to do it yourself no prob.

Replaced the belt tensionor over the weekend and now starts on one try. But if I do not let the car warm up I almost stall. Bad gas smell coming from the tail pipe still have the thud thud thud and smell of gas coming from engine. HELP

The Egr valve would also cause your symptoms, and if it's a vacuum operated one (you didn't give the year of your van) that would account for the thud noise in the engine compartment.