Where is the vacuum modulator located on the transmission of a 1998 Pontiac grand prix gtp.

There is a vacuum hose connected to it on the passenger side of the transmission It is a silver colored round in shape about 2 inches in diameter.

Here's a link to where it's located. Engine Control Unit .Here's something else I ran into for you to read. Engine Control Module ECM can fail Pontiac Grand Prix Exhaust and Emissions

On the front side of the transmission. It has a vacuum hose going to it. Check the hose first.

everything will cross over but the engine and transmission in the gtp are suppose be heavier duty built

As you see I provided you the models you can apply the transmission :The 4T65E-HD (code MN7) is a heavy duty version of the 4T65-E used with more powerful engines such as the LS4 V8 and L67/L32 supercharged V6. Applications: 2.93:1 MN7 Pontiac Bonneville SSEi L67 Chevrolet Impala L67 Chevrolet Monte Carlo L67 Pontiac Grand Prix GTP/GXP Buick Regal GS Buick Riviera L67 (97-99) So ,yes you can!

Your fuel pump is located inside your gas tank.

Your transmission for the GTP should be the 4T65-HD. If in fact it is not then that could very well be the problem. The 4T65-E is for the other 3.8L naturally aspirated models.

The best place you'll ever find parts and service for the GTP is www.zzperformance.com

They have their headquarters garage and then several authorized satellite locations in a few states. They make their living on working only with the GTP exclusively.

may not be fuel related,replace crank shaft sensor,if it isnt that ,,,ignition module